Calculating a 20% discount by multiplying by 0.8333?
up vote
7
down vote
favorite
I've been looking at some discounted prices of goods.
They are listed with a $20%$ discount, so to work this out I did:
$$ $25.45 cdot 0.8333 = $21.21. $$
But their total was $20.34$, which I presume they got by doing $25.42 cdot 0.8$.
To apply a $20%$ discount or to subtract $20%$, which of the above is correct?
percentages
|
show 3 more comments
up vote
7
down vote
favorite
I've been looking at some discounted prices of goods.
They are listed with a $20%$ discount, so to work this out I did:
$$ $25.45 cdot 0.8333 = $21.21. $$
But their total was $20.34$, which I presume they got by doing $25.42 cdot 0.8$.
To apply a $20%$ discount or to subtract $20%$, which of the above is correct?
percentages
2
$25.42times (1 - 20/100)$
– Éric Guirbal
Jun 2 '17 at 15:58
37
why multiply by $5/6$?
– Dando18
Jun 2 '17 at 16:00
11
You tell us neither where the $25.45$ comes from, nor the $0.8333$.
– Carsten S
Jun 2 '17 at 17:39
25
@CarstenS It's blatantly obvious that the 25.45 is the original price of the goods...
– The Great Duck
Jun 2 '17 at 20:24
11
Care to check your figures. You quote 25.45 then 25.42. Can't both be accurate.
– Tim
Jun 3 '17 at 14:16
|
show 3 more comments
up vote
7
down vote
favorite
up vote
7
down vote
favorite
I've been looking at some discounted prices of goods.
They are listed with a $20%$ discount, so to work this out I did:
$$ $25.45 cdot 0.8333 = $21.21. $$
But their total was $20.34$, which I presume they got by doing $25.42 cdot 0.8$.
To apply a $20%$ discount or to subtract $20%$, which of the above is correct?
percentages
I've been looking at some discounted prices of goods.
They are listed with a $20%$ discount, so to work this out I did:
$$ $25.45 cdot 0.8333 = $21.21. $$
But their total was $20.34$, which I presume they got by doing $25.42 cdot 0.8$.
To apply a $20%$ discount or to subtract $20%$, which of the above is correct?
percentages
percentages
edited Jun 2 '17 at 19:04
Chappers
55.6k74192
55.6k74192
asked Jun 2 '17 at 15:55
sam
156115
156115
2
$25.42times (1 - 20/100)$
– Éric Guirbal
Jun 2 '17 at 15:58
37
why multiply by $5/6$?
– Dando18
Jun 2 '17 at 16:00
11
You tell us neither where the $25.45$ comes from, nor the $0.8333$.
– Carsten S
Jun 2 '17 at 17:39
25
@CarstenS It's blatantly obvious that the 25.45 is the original price of the goods...
– The Great Duck
Jun 2 '17 at 20:24
11
Care to check your figures. You quote 25.45 then 25.42. Can't both be accurate.
– Tim
Jun 3 '17 at 14:16
|
show 3 more comments
2
$25.42times (1 - 20/100)$
– Éric Guirbal
Jun 2 '17 at 15:58
37
why multiply by $5/6$?
– Dando18
Jun 2 '17 at 16:00
11
You tell us neither where the $25.45$ comes from, nor the $0.8333$.
– Carsten S
Jun 2 '17 at 17:39
25
@CarstenS It's blatantly obvious that the 25.45 is the original price of the goods...
– The Great Duck
Jun 2 '17 at 20:24
11
Care to check your figures. You quote 25.45 then 25.42. Can't both be accurate.
– Tim
Jun 3 '17 at 14:16
2
2
$25.42times (1 - 20/100)$
– Éric Guirbal
Jun 2 '17 at 15:58
$25.42times (1 - 20/100)$
– Éric Guirbal
Jun 2 '17 at 15:58
37
37
why multiply by $5/6$?
– Dando18
Jun 2 '17 at 16:00
why multiply by $5/6$?
– Dando18
Jun 2 '17 at 16:00
11
11
You tell us neither where the $25.45$ comes from, nor the $0.8333$.
– Carsten S
Jun 2 '17 at 17:39
You tell us neither where the $25.45$ comes from, nor the $0.8333$.
– Carsten S
Jun 2 '17 at 17:39
25
25
@CarstenS It's blatantly obvious that the 25.45 is the original price of the goods...
– The Great Duck
Jun 2 '17 at 20:24
@CarstenS It's blatantly obvious that the 25.45 is the original price of the goods...
– The Great Duck
Jun 2 '17 at 20:24
11
11
Care to check your figures. You quote 25.45 then 25.42. Can't both be accurate.
– Tim
Jun 3 '17 at 14:16
Care to check your figures. You quote 25.45 then 25.42. Can't both be accurate.
– Tim
Jun 3 '17 at 14:16
|
show 3 more comments
6 Answers
6
active
oldest
votes
up vote
73
down vote
accepted
A $20%$ discount means that the price is $80%$ of what it was originally, so you multiply by $1-0.2=0.8$.
$0.8dot{3}$ is $1/1.2$, which is used to find out the original price when you have been given $120%$ of it (if there's $20%$ tax included in it, for example)
4
So $1-r$ is not the same as $frac{1}{1+r}$. This is related to the fact that $(1-r)(1+r)$ is not one exactly (physicists would say it is $1$ only to the first order in $r$). Another well-known way of thinking of it is if you first remove $frac{r}{100}$ percent, then add $frac{r}{100}$ percent of the resulting amount, then you're not back where you started.
– Jeppe Stig Nielsen
Jun 4 '17 at 7:17
add a comment |
up vote
17
down vote
Note that multiplying by $0.83bar3$ is really dividing by $1.2$. In order to know which one is right, you need to keep in mind which number represents $100%$, or the origin. Calculating percentages from the origin is done by multiplying, while recovering the origin from some given percentage is done by dividing.
So finding $80%$ of a price is done by multiplying with $0.8$. If you have the $80%$ price and want to find the original price, you divide by $0.8$ (which becomes multiplying by $1.25$).
So multiplying with $0.83bar3$, when we're talking about $20%$ and not $16.6bar6%$, is, as mentioned above, really dividing by $1.2$. That means that what we find is the original price when we're given the new price after a $20%$ price increase. That's not the same as finding $80%$.
add a comment |
up vote
14
down vote
An $x %$ discount normally means you subtract $x %$ of the original price.
2
This does not at all answer the question that was asked.
– The Great Duck
Jun 2 '17 at 20:25
28
@TheGreatDuck I disagree.
– Dan Henderson
Jun 2 '17 at 22:46
3
@TheGreatDuck What don't you understand about my answer?
– Robert Israel
Jun 3 '17 at 2:13
4
@TheGreatDuckNot an ounce of multiplication is even mentioned here
Well, "x% of the original price" counts as a multiplication in my books. You take the "original price", then multiply it by "x%" which is in this case "a 20% discount" according to the OP, meaning you multiply by $20% = 0.2,$. Once you subtract that from the original price $,x,$, what's left to pay is $,x - 0.2 x = 0.8 x,$. Not sure what your problem was with this answer.
– dxiv
Jun 3 '17 at 6:20
2
@TheGreatDuck I would expect the OP to very easily connect thex% discount
from this answer toa 20% discount
from the posted question, as to reckon that $x=20,$.
– dxiv
Jun 3 '17 at 6:26
|
show 8 more comments
up vote
9
down vote
A $20%$ increase in price can be computed by dividing by $0.83333ldots$ (with $3$ repeating), but that does not mean a $20%$ decrease results from multiplying by that number. The reason is that in the latter problem we're dealing with $20%$ of a different quantity. A $20%$ decrease is computed by multiplying by $1-0.2 = 0.8.$
For example, if you cut a $$100$ price by $50%$ and then increase it by $50%,$ you don't get back $$100,$ but rather $$75.$
(Multiplying by $1.2$ is simpler than dividing by $0.83333ldots$ and is more accurate unless you know how to take the infinite repetition of the $3$ into account (and calculators that I've seen do not know how to do that).
Postscript:
begin{align}
80% text{ of } $25.45 & = $25.45 times 0.8 = $20.36 \[10pt]
80% text{ of } $25.45 & = $25.45 times frac 4 5 = $5.09times 4 = $20.36 \[10pt]
$25.45 & = frac 5 4 times $20.36 = 5times$5.09 \[10pt]
$25.45 & = 1.25 times $20.36 = 125% text{ of } $20.36
end{align}
Whatcha mean infinite? You'd only need enough precision to figure out the partial penny (e.g., a tenth of a penny). Even the partial penny only affects rounding, if you do that. If you know the tenth-of-a-penny, there's no reason to figure out the hundredth or thousandth (or infinitth)
– TOOGAM
Jun 3 '17 at 6:18
3
@TOOGAM Not necessarily, you might be buying a thousand units. Your suggestion could mean that you end up paying £833.00 for a thousand one pound items discounted by a sixth, where the correct amount would be £833.33. It's not a big difference, but it's a difference, and that kind of thing tends to make accountants unhappy.
– Mike Scott
Jun 3 '17 at 12:14
1
This is a simple explanation, and makes good sense. +1 Lots of folk (in real life) seem to not have grasped your middle para.
– Tim
Jun 3 '17 at 14:15
@TOOGAM : Rounding before the last step is far more hazardous than you seem to realize.
– Michael Hardy
Jun 4 '17 at 23:38
@MikeScott and Michael Hardy: Obviously rounding too early can affect things. Why'd both of you think there's another step, such as multiplying the $25.45 by a thousand? Both of you seem to indicate there is at least one more step, but the question didn't say anything about a thousand units, nor did the question specify that the 20% discount is per final order (instead of per item). The question didn't say $25.45 "each unit". After discussing "the goods", it says "their total was 20.34", suggesting that we've already added (to handle quantities), and are looking at the more final totals.
– TOOGAM
Jun 5 '17 at 2:07
|
show 1 more comment
up vote
3
down vote
The trouble with percentages (and a major source of math anxiety when people are doing mental arithmetic) is that they are inherently ambiguous. The question most people are not trained to ask is percent of what. Most of the problems occur because when percentages are use the percent of what is not explicitly specified.
In this question a 20% discount probably means deduct 20% from the stated price. But, unless this is stated very explicitly there is still room for confusion. If it really is 20% off the stated price then the correct result is price*0.8.
But it is a little ambiguous. Here is an example. In the UK we have a sales tax called VAT levied at 20%. But 20% of what? Legally it is 20% of the pre-tax price but shops have to quote the total price after tax has been applied (something the USA ought to mandate to avoid confusion for foreigners if not locals as well). So if a discount is described as "we pay your VAT" it sounds like a 20% discount to many but is actually a reduction of ~16.7% on the stated price (1/1.2 since the stated price is pre-tax price*1.2).
So, if you want to avoid confusion with percentages, always ask percent of what?
And, if you are going to be a good scientist always specify explicitly what your percentages mean. If your drug "reduces deaths by 20%" be very explicit in saying from what base (and tell us what percentage of people die without the drug so we can judge the absolute risk: 10 deaths reduced to 8 is a significant result when only 100 people were in the trial but not much when there are 10,000 people in the trial).
add a comment |
up vote
0
down vote
You cannot multiply anything by 0.8333 to arrive at 80% of the original. All you end up with is 83.33% of the original. So to get a discount of 20%, you need to calculate 80% 0f that figure. Don't know where '.8333' came from! That only gives a discount of 16.7%. X times 0.8 does it right. To get that discounted figure back to its original, multiply by 1.25.
Please explain why you thought 0.8333 was a good idea, and also edit the question with one start point value - you wrote two different ones.
Basic answer, the 'less 20%' - aka times 0.8 can be the only way. Even if tax was applied to the item before and after discount, it would make no difference.
We have phantom downvoters on this site too! I need to know what the reason is, please!
– Tim
Jun 4 '17 at 16:44
1
I didn't downvote, though my guess would be that downvoters didn't feel that this answer added anything beyond what's already been covered in prior answers. Repetition makes for clutter and consumes readers' time for no return. You'd probably have gotten a lot of upvotes if this were the first answer.
– Nat
Jun 4 '17 at 21:53
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2307126%2fcalculating-a-20-discount-by-multiplying-by-0-8333%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
6 Answers
6
active
oldest
votes
6 Answers
6
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
73
down vote
accepted
A $20%$ discount means that the price is $80%$ of what it was originally, so you multiply by $1-0.2=0.8$.
$0.8dot{3}$ is $1/1.2$, which is used to find out the original price when you have been given $120%$ of it (if there's $20%$ tax included in it, for example)
4
So $1-r$ is not the same as $frac{1}{1+r}$. This is related to the fact that $(1-r)(1+r)$ is not one exactly (physicists would say it is $1$ only to the first order in $r$). Another well-known way of thinking of it is if you first remove $frac{r}{100}$ percent, then add $frac{r}{100}$ percent of the resulting amount, then you're not back where you started.
– Jeppe Stig Nielsen
Jun 4 '17 at 7:17
add a comment |
up vote
73
down vote
accepted
A $20%$ discount means that the price is $80%$ of what it was originally, so you multiply by $1-0.2=0.8$.
$0.8dot{3}$ is $1/1.2$, which is used to find out the original price when you have been given $120%$ of it (if there's $20%$ tax included in it, for example)
4
So $1-r$ is not the same as $frac{1}{1+r}$. This is related to the fact that $(1-r)(1+r)$ is not one exactly (physicists would say it is $1$ only to the first order in $r$). Another well-known way of thinking of it is if you first remove $frac{r}{100}$ percent, then add $frac{r}{100}$ percent of the resulting amount, then you're not back where you started.
– Jeppe Stig Nielsen
Jun 4 '17 at 7:17
add a comment |
up vote
73
down vote
accepted
up vote
73
down vote
accepted
A $20%$ discount means that the price is $80%$ of what it was originally, so you multiply by $1-0.2=0.8$.
$0.8dot{3}$ is $1/1.2$, which is used to find out the original price when you have been given $120%$ of it (if there's $20%$ tax included in it, for example)
A $20%$ discount means that the price is $80%$ of what it was originally, so you multiply by $1-0.2=0.8$.
$0.8dot{3}$ is $1/1.2$, which is used to find out the original price when you have been given $120%$ of it (if there's $20%$ tax included in it, for example)
answered Jun 2 '17 at 16:00
Chappers
55.6k74192
55.6k74192
4
So $1-r$ is not the same as $frac{1}{1+r}$. This is related to the fact that $(1-r)(1+r)$ is not one exactly (physicists would say it is $1$ only to the first order in $r$). Another well-known way of thinking of it is if you first remove $frac{r}{100}$ percent, then add $frac{r}{100}$ percent of the resulting amount, then you're not back where you started.
– Jeppe Stig Nielsen
Jun 4 '17 at 7:17
add a comment |
4
So $1-r$ is not the same as $frac{1}{1+r}$. This is related to the fact that $(1-r)(1+r)$ is not one exactly (physicists would say it is $1$ only to the first order in $r$). Another well-known way of thinking of it is if you first remove $frac{r}{100}$ percent, then add $frac{r}{100}$ percent of the resulting amount, then you're not back where you started.
– Jeppe Stig Nielsen
Jun 4 '17 at 7:17
4
4
So $1-r$ is not the same as $frac{1}{1+r}$. This is related to the fact that $(1-r)(1+r)$ is not one exactly (physicists would say it is $1$ only to the first order in $r$). Another well-known way of thinking of it is if you first remove $frac{r}{100}$ percent, then add $frac{r}{100}$ percent of the resulting amount, then you're not back where you started.
– Jeppe Stig Nielsen
Jun 4 '17 at 7:17
So $1-r$ is not the same as $frac{1}{1+r}$. This is related to the fact that $(1-r)(1+r)$ is not one exactly (physicists would say it is $1$ only to the first order in $r$). Another well-known way of thinking of it is if you first remove $frac{r}{100}$ percent, then add $frac{r}{100}$ percent of the resulting amount, then you're not back where you started.
– Jeppe Stig Nielsen
Jun 4 '17 at 7:17
add a comment |
up vote
17
down vote
Note that multiplying by $0.83bar3$ is really dividing by $1.2$. In order to know which one is right, you need to keep in mind which number represents $100%$, or the origin. Calculating percentages from the origin is done by multiplying, while recovering the origin from some given percentage is done by dividing.
So finding $80%$ of a price is done by multiplying with $0.8$. If you have the $80%$ price and want to find the original price, you divide by $0.8$ (which becomes multiplying by $1.25$).
So multiplying with $0.83bar3$, when we're talking about $20%$ and not $16.6bar6%$, is, as mentioned above, really dividing by $1.2$. That means that what we find is the original price when we're given the new price after a $20%$ price increase. That's not the same as finding $80%$.
add a comment |
up vote
17
down vote
Note that multiplying by $0.83bar3$ is really dividing by $1.2$. In order to know which one is right, you need to keep in mind which number represents $100%$, or the origin. Calculating percentages from the origin is done by multiplying, while recovering the origin from some given percentage is done by dividing.
So finding $80%$ of a price is done by multiplying with $0.8$. If you have the $80%$ price and want to find the original price, you divide by $0.8$ (which becomes multiplying by $1.25$).
So multiplying with $0.83bar3$, when we're talking about $20%$ and not $16.6bar6%$, is, as mentioned above, really dividing by $1.2$. That means that what we find is the original price when we're given the new price after a $20%$ price increase. That's not the same as finding $80%$.
add a comment |
up vote
17
down vote
up vote
17
down vote
Note that multiplying by $0.83bar3$ is really dividing by $1.2$. In order to know which one is right, you need to keep in mind which number represents $100%$, or the origin. Calculating percentages from the origin is done by multiplying, while recovering the origin from some given percentage is done by dividing.
So finding $80%$ of a price is done by multiplying with $0.8$. If you have the $80%$ price and want to find the original price, you divide by $0.8$ (which becomes multiplying by $1.25$).
So multiplying with $0.83bar3$, when we're talking about $20%$ and not $16.6bar6%$, is, as mentioned above, really dividing by $1.2$. That means that what we find is the original price when we're given the new price after a $20%$ price increase. That's not the same as finding $80%$.
Note that multiplying by $0.83bar3$ is really dividing by $1.2$. In order to know which one is right, you need to keep in mind which number represents $100%$, or the origin. Calculating percentages from the origin is done by multiplying, while recovering the origin from some given percentage is done by dividing.
So finding $80%$ of a price is done by multiplying with $0.8$. If you have the $80%$ price and want to find the original price, you divide by $0.8$ (which becomes multiplying by $1.25$).
So multiplying with $0.83bar3$, when we're talking about $20%$ and not $16.6bar6%$, is, as mentioned above, really dividing by $1.2$. That means that what we find is the original price when we're given the new price after a $20%$ price increase. That's not the same as finding $80%$.
edited Jun 2 '17 at 16:06
answered Jun 2 '17 at 16:01
Arthur
110k7104186
110k7104186
add a comment |
add a comment |
up vote
14
down vote
An $x %$ discount normally means you subtract $x %$ of the original price.
2
This does not at all answer the question that was asked.
– The Great Duck
Jun 2 '17 at 20:25
28
@TheGreatDuck I disagree.
– Dan Henderson
Jun 2 '17 at 22:46
3
@TheGreatDuck What don't you understand about my answer?
– Robert Israel
Jun 3 '17 at 2:13
4
@TheGreatDuckNot an ounce of multiplication is even mentioned here
Well, "x% of the original price" counts as a multiplication in my books. You take the "original price", then multiply it by "x%" which is in this case "a 20% discount" according to the OP, meaning you multiply by $20% = 0.2,$. Once you subtract that from the original price $,x,$, what's left to pay is $,x - 0.2 x = 0.8 x,$. Not sure what your problem was with this answer.
– dxiv
Jun 3 '17 at 6:20
2
@TheGreatDuck I would expect the OP to very easily connect thex% discount
from this answer toa 20% discount
from the posted question, as to reckon that $x=20,$.
– dxiv
Jun 3 '17 at 6:26
|
show 8 more comments
up vote
14
down vote
An $x %$ discount normally means you subtract $x %$ of the original price.
2
This does not at all answer the question that was asked.
– The Great Duck
Jun 2 '17 at 20:25
28
@TheGreatDuck I disagree.
– Dan Henderson
Jun 2 '17 at 22:46
3
@TheGreatDuck What don't you understand about my answer?
– Robert Israel
Jun 3 '17 at 2:13
4
@TheGreatDuckNot an ounce of multiplication is even mentioned here
Well, "x% of the original price" counts as a multiplication in my books. You take the "original price", then multiply it by "x%" which is in this case "a 20% discount" according to the OP, meaning you multiply by $20% = 0.2,$. Once you subtract that from the original price $,x,$, what's left to pay is $,x - 0.2 x = 0.8 x,$. Not sure what your problem was with this answer.
– dxiv
Jun 3 '17 at 6:20
2
@TheGreatDuck I would expect the OP to very easily connect thex% discount
from this answer toa 20% discount
from the posted question, as to reckon that $x=20,$.
– dxiv
Jun 3 '17 at 6:26
|
show 8 more comments
up vote
14
down vote
up vote
14
down vote
An $x %$ discount normally means you subtract $x %$ of the original price.
An $x %$ discount normally means you subtract $x %$ of the original price.
answered Jun 2 '17 at 15:59
Robert Israel
316k23206457
316k23206457
2
This does not at all answer the question that was asked.
– The Great Duck
Jun 2 '17 at 20:25
28
@TheGreatDuck I disagree.
– Dan Henderson
Jun 2 '17 at 22:46
3
@TheGreatDuck What don't you understand about my answer?
– Robert Israel
Jun 3 '17 at 2:13
4
@TheGreatDuckNot an ounce of multiplication is even mentioned here
Well, "x% of the original price" counts as a multiplication in my books. You take the "original price", then multiply it by "x%" which is in this case "a 20% discount" according to the OP, meaning you multiply by $20% = 0.2,$. Once you subtract that from the original price $,x,$, what's left to pay is $,x - 0.2 x = 0.8 x,$. Not sure what your problem was with this answer.
– dxiv
Jun 3 '17 at 6:20
2
@TheGreatDuck I would expect the OP to very easily connect thex% discount
from this answer toa 20% discount
from the posted question, as to reckon that $x=20,$.
– dxiv
Jun 3 '17 at 6:26
|
show 8 more comments
2
This does not at all answer the question that was asked.
– The Great Duck
Jun 2 '17 at 20:25
28
@TheGreatDuck I disagree.
– Dan Henderson
Jun 2 '17 at 22:46
3
@TheGreatDuck What don't you understand about my answer?
– Robert Israel
Jun 3 '17 at 2:13
4
@TheGreatDuckNot an ounce of multiplication is even mentioned here
Well, "x% of the original price" counts as a multiplication in my books. You take the "original price", then multiply it by "x%" which is in this case "a 20% discount" according to the OP, meaning you multiply by $20% = 0.2,$. Once you subtract that from the original price $,x,$, what's left to pay is $,x - 0.2 x = 0.8 x,$. Not sure what your problem was with this answer.
– dxiv
Jun 3 '17 at 6:20
2
@TheGreatDuck I would expect the OP to very easily connect thex% discount
from this answer toa 20% discount
from the posted question, as to reckon that $x=20,$.
– dxiv
Jun 3 '17 at 6:26
2
2
This does not at all answer the question that was asked.
– The Great Duck
Jun 2 '17 at 20:25
This does not at all answer the question that was asked.
– The Great Duck
Jun 2 '17 at 20:25
28
28
@TheGreatDuck I disagree.
– Dan Henderson
Jun 2 '17 at 22:46
@TheGreatDuck I disagree.
– Dan Henderson
Jun 2 '17 at 22:46
3
3
@TheGreatDuck What don't you understand about my answer?
– Robert Israel
Jun 3 '17 at 2:13
@TheGreatDuck What don't you understand about my answer?
– Robert Israel
Jun 3 '17 at 2:13
4
4
@TheGreatDuck
Not an ounce of multiplication is even mentioned here
Well, "x% of the original price" counts as a multiplication in my books. You take the "original price", then multiply it by "x%" which is in this case "a 20% discount" according to the OP, meaning you multiply by $20% = 0.2,$. Once you subtract that from the original price $,x,$, what's left to pay is $,x - 0.2 x = 0.8 x,$. Not sure what your problem was with this answer.– dxiv
Jun 3 '17 at 6:20
@TheGreatDuck
Not an ounce of multiplication is even mentioned here
Well, "x% of the original price" counts as a multiplication in my books. You take the "original price", then multiply it by "x%" which is in this case "a 20% discount" according to the OP, meaning you multiply by $20% = 0.2,$. Once you subtract that from the original price $,x,$, what's left to pay is $,x - 0.2 x = 0.8 x,$. Not sure what your problem was with this answer.– dxiv
Jun 3 '17 at 6:20
2
2
@TheGreatDuck I would expect the OP to very easily connect the
x% discount
from this answer to a 20% discount
from the posted question, as to reckon that $x=20,$.– dxiv
Jun 3 '17 at 6:26
@TheGreatDuck I would expect the OP to very easily connect the
x% discount
from this answer to a 20% discount
from the posted question, as to reckon that $x=20,$.– dxiv
Jun 3 '17 at 6:26
|
show 8 more comments
up vote
9
down vote
A $20%$ increase in price can be computed by dividing by $0.83333ldots$ (with $3$ repeating), but that does not mean a $20%$ decrease results from multiplying by that number. The reason is that in the latter problem we're dealing with $20%$ of a different quantity. A $20%$ decrease is computed by multiplying by $1-0.2 = 0.8.$
For example, if you cut a $$100$ price by $50%$ and then increase it by $50%,$ you don't get back $$100,$ but rather $$75.$
(Multiplying by $1.2$ is simpler than dividing by $0.83333ldots$ and is more accurate unless you know how to take the infinite repetition of the $3$ into account (and calculators that I've seen do not know how to do that).
Postscript:
begin{align}
80% text{ of } $25.45 & = $25.45 times 0.8 = $20.36 \[10pt]
80% text{ of } $25.45 & = $25.45 times frac 4 5 = $5.09times 4 = $20.36 \[10pt]
$25.45 & = frac 5 4 times $20.36 = 5times$5.09 \[10pt]
$25.45 & = 1.25 times $20.36 = 125% text{ of } $20.36
end{align}
Whatcha mean infinite? You'd only need enough precision to figure out the partial penny (e.g., a tenth of a penny). Even the partial penny only affects rounding, if you do that. If you know the tenth-of-a-penny, there's no reason to figure out the hundredth or thousandth (or infinitth)
– TOOGAM
Jun 3 '17 at 6:18
3
@TOOGAM Not necessarily, you might be buying a thousand units. Your suggestion could mean that you end up paying £833.00 for a thousand one pound items discounted by a sixth, where the correct amount would be £833.33. It's not a big difference, but it's a difference, and that kind of thing tends to make accountants unhappy.
– Mike Scott
Jun 3 '17 at 12:14
1
This is a simple explanation, and makes good sense. +1 Lots of folk (in real life) seem to not have grasped your middle para.
– Tim
Jun 3 '17 at 14:15
@TOOGAM : Rounding before the last step is far more hazardous than you seem to realize.
– Michael Hardy
Jun 4 '17 at 23:38
@MikeScott and Michael Hardy: Obviously rounding too early can affect things. Why'd both of you think there's another step, such as multiplying the $25.45 by a thousand? Both of you seem to indicate there is at least one more step, but the question didn't say anything about a thousand units, nor did the question specify that the 20% discount is per final order (instead of per item). The question didn't say $25.45 "each unit". After discussing "the goods", it says "their total was 20.34", suggesting that we've already added (to handle quantities), and are looking at the more final totals.
– TOOGAM
Jun 5 '17 at 2:07
|
show 1 more comment
up vote
9
down vote
A $20%$ increase in price can be computed by dividing by $0.83333ldots$ (with $3$ repeating), but that does not mean a $20%$ decrease results from multiplying by that number. The reason is that in the latter problem we're dealing with $20%$ of a different quantity. A $20%$ decrease is computed by multiplying by $1-0.2 = 0.8.$
For example, if you cut a $$100$ price by $50%$ and then increase it by $50%,$ you don't get back $$100,$ but rather $$75.$
(Multiplying by $1.2$ is simpler than dividing by $0.83333ldots$ and is more accurate unless you know how to take the infinite repetition of the $3$ into account (and calculators that I've seen do not know how to do that).
Postscript:
begin{align}
80% text{ of } $25.45 & = $25.45 times 0.8 = $20.36 \[10pt]
80% text{ of } $25.45 & = $25.45 times frac 4 5 = $5.09times 4 = $20.36 \[10pt]
$25.45 & = frac 5 4 times $20.36 = 5times$5.09 \[10pt]
$25.45 & = 1.25 times $20.36 = 125% text{ of } $20.36
end{align}
Whatcha mean infinite? You'd only need enough precision to figure out the partial penny (e.g., a tenth of a penny). Even the partial penny only affects rounding, if you do that. If you know the tenth-of-a-penny, there's no reason to figure out the hundredth or thousandth (or infinitth)
– TOOGAM
Jun 3 '17 at 6:18
3
@TOOGAM Not necessarily, you might be buying a thousand units. Your suggestion could mean that you end up paying £833.00 for a thousand one pound items discounted by a sixth, where the correct amount would be £833.33. It's not a big difference, but it's a difference, and that kind of thing tends to make accountants unhappy.
– Mike Scott
Jun 3 '17 at 12:14
1
This is a simple explanation, and makes good sense. +1 Lots of folk (in real life) seem to not have grasped your middle para.
– Tim
Jun 3 '17 at 14:15
@TOOGAM : Rounding before the last step is far more hazardous than you seem to realize.
– Michael Hardy
Jun 4 '17 at 23:38
@MikeScott and Michael Hardy: Obviously rounding too early can affect things. Why'd both of you think there's another step, such as multiplying the $25.45 by a thousand? Both of you seem to indicate there is at least one more step, but the question didn't say anything about a thousand units, nor did the question specify that the 20% discount is per final order (instead of per item). The question didn't say $25.45 "each unit". After discussing "the goods", it says "their total was 20.34", suggesting that we've already added (to handle quantities), and are looking at the more final totals.
– TOOGAM
Jun 5 '17 at 2:07
|
show 1 more comment
up vote
9
down vote
up vote
9
down vote
A $20%$ increase in price can be computed by dividing by $0.83333ldots$ (with $3$ repeating), but that does not mean a $20%$ decrease results from multiplying by that number. The reason is that in the latter problem we're dealing with $20%$ of a different quantity. A $20%$ decrease is computed by multiplying by $1-0.2 = 0.8.$
For example, if you cut a $$100$ price by $50%$ and then increase it by $50%,$ you don't get back $$100,$ but rather $$75.$
(Multiplying by $1.2$ is simpler than dividing by $0.83333ldots$ and is more accurate unless you know how to take the infinite repetition of the $3$ into account (and calculators that I've seen do not know how to do that).
Postscript:
begin{align}
80% text{ of } $25.45 & = $25.45 times 0.8 = $20.36 \[10pt]
80% text{ of } $25.45 & = $25.45 times frac 4 5 = $5.09times 4 = $20.36 \[10pt]
$25.45 & = frac 5 4 times $20.36 = 5times$5.09 \[10pt]
$25.45 & = 1.25 times $20.36 = 125% text{ of } $20.36
end{align}
A $20%$ increase in price can be computed by dividing by $0.83333ldots$ (with $3$ repeating), but that does not mean a $20%$ decrease results from multiplying by that number. The reason is that in the latter problem we're dealing with $20%$ of a different quantity. A $20%$ decrease is computed by multiplying by $1-0.2 = 0.8.$
For example, if you cut a $$100$ price by $50%$ and then increase it by $50%,$ you don't get back $$100,$ but rather $$75.$
(Multiplying by $1.2$ is simpler than dividing by $0.83333ldots$ and is more accurate unless you know how to take the infinite repetition of the $3$ into account (and calculators that I've seen do not know how to do that).
Postscript:
begin{align}
80% text{ of } $25.45 & = $25.45 times 0.8 = $20.36 \[10pt]
80% text{ of } $25.45 & = $25.45 times frac 4 5 = $5.09times 4 = $20.36 \[10pt]
$25.45 & = frac 5 4 times $20.36 = 5times$5.09 \[10pt]
$25.45 & = 1.25 times $20.36 = 125% text{ of } $20.36
end{align}
edited Jun 5 '17 at 16:49
answered Jun 2 '17 at 16:19
Michael Hardy
1
1
Whatcha mean infinite? You'd only need enough precision to figure out the partial penny (e.g., a tenth of a penny). Even the partial penny only affects rounding, if you do that. If you know the tenth-of-a-penny, there's no reason to figure out the hundredth or thousandth (or infinitth)
– TOOGAM
Jun 3 '17 at 6:18
3
@TOOGAM Not necessarily, you might be buying a thousand units. Your suggestion could mean that you end up paying £833.00 for a thousand one pound items discounted by a sixth, where the correct amount would be £833.33. It's not a big difference, but it's a difference, and that kind of thing tends to make accountants unhappy.
– Mike Scott
Jun 3 '17 at 12:14
1
This is a simple explanation, and makes good sense. +1 Lots of folk (in real life) seem to not have grasped your middle para.
– Tim
Jun 3 '17 at 14:15
@TOOGAM : Rounding before the last step is far more hazardous than you seem to realize.
– Michael Hardy
Jun 4 '17 at 23:38
@MikeScott and Michael Hardy: Obviously rounding too early can affect things. Why'd both of you think there's another step, such as multiplying the $25.45 by a thousand? Both of you seem to indicate there is at least one more step, but the question didn't say anything about a thousand units, nor did the question specify that the 20% discount is per final order (instead of per item). The question didn't say $25.45 "each unit". After discussing "the goods", it says "their total was 20.34", suggesting that we've already added (to handle quantities), and are looking at the more final totals.
– TOOGAM
Jun 5 '17 at 2:07
|
show 1 more comment
Whatcha mean infinite? You'd only need enough precision to figure out the partial penny (e.g., a tenth of a penny). Even the partial penny only affects rounding, if you do that. If you know the tenth-of-a-penny, there's no reason to figure out the hundredth or thousandth (or infinitth)
– TOOGAM
Jun 3 '17 at 6:18
3
@TOOGAM Not necessarily, you might be buying a thousand units. Your suggestion could mean that you end up paying £833.00 for a thousand one pound items discounted by a sixth, where the correct amount would be £833.33. It's not a big difference, but it's a difference, and that kind of thing tends to make accountants unhappy.
– Mike Scott
Jun 3 '17 at 12:14
1
This is a simple explanation, and makes good sense. +1 Lots of folk (in real life) seem to not have grasped your middle para.
– Tim
Jun 3 '17 at 14:15
@TOOGAM : Rounding before the last step is far more hazardous than you seem to realize.
– Michael Hardy
Jun 4 '17 at 23:38
@MikeScott and Michael Hardy: Obviously rounding too early can affect things. Why'd both of you think there's another step, such as multiplying the $25.45 by a thousand? Both of you seem to indicate there is at least one more step, but the question didn't say anything about a thousand units, nor did the question specify that the 20% discount is per final order (instead of per item). The question didn't say $25.45 "each unit". After discussing "the goods", it says "their total was 20.34", suggesting that we've already added (to handle quantities), and are looking at the more final totals.
– TOOGAM
Jun 5 '17 at 2:07
Whatcha mean infinite? You'd only need enough precision to figure out the partial penny (e.g., a tenth of a penny). Even the partial penny only affects rounding, if you do that. If you know the tenth-of-a-penny, there's no reason to figure out the hundredth or thousandth (or infinitth)
– TOOGAM
Jun 3 '17 at 6:18
Whatcha mean infinite? You'd only need enough precision to figure out the partial penny (e.g., a tenth of a penny). Even the partial penny only affects rounding, if you do that. If you know the tenth-of-a-penny, there's no reason to figure out the hundredth or thousandth (or infinitth)
– TOOGAM
Jun 3 '17 at 6:18
3
3
@TOOGAM Not necessarily, you might be buying a thousand units. Your suggestion could mean that you end up paying £833.00 for a thousand one pound items discounted by a sixth, where the correct amount would be £833.33. It's not a big difference, but it's a difference, and that kind of thing tends to make accountants unhappy.
– Mike Scott
Jun 3 '17 at 12:14
@TOOGAM Not necessarily, you might be buying a thousand units. Your suggestion could mean that you end up paying £833.00 for a thousand one pound items discounted by a sixth, where the correct amount would be £833.33. It's not a big difference, but it's a difference, and that kind of thing tends to make accountants unhappy.
– Mike Scott
Jun 3 '17 at 12:14
1
1
This is a simple explanation, and makes good sense. +1 Lots of folk (in real life) seem to not have grasped your middle para.
– Tim
Jun 3 '17 at 14:15
This is a simple explanation, and makes good sense. +1 Lots of folk (in real life) seem to not have grasped your middle para.
– Tim
Jun 3 '17 at 14:15
@TOOGAM : Rounding before the last step is far more hazardous than you seem to realize.
– Michael Hardy
Jun 4 '17 at 23:38
@TOOGAM : Rounding before the last step is far more hazardous than you seem to realize.
– Michael Hardy
Jun 4 '17 at 23:38
@MikeScott and Michael Hardy: Obviously rounding too early can affect things. Why'd both of you think there's another step, such as multiplying the $25.45 by a thousand? Both of you seem to indicate there is at least one more step, but the question didn't say anything about a thousand units, nor did the question specify that the 20% discount is per final order (instead of per item). The question didn't say $25.45 "each unit". After discussing "the goods", it says "their total was 20.34", suggesting that we've already added (to handle quantities), and are looking at the more final totals.
– TOOGAM
Jun 5 '17 at 2:07
@MikeScott and Michael Hardy: Obviously rounding too early can affect things. Why'd both of you think there's another step, such as multiplying the $25.45 by a thousand? Both of you seem to indicate there is at least one more step, but the question didn't say anything about a thousand units, nor did the question specify that the 20% discount is per final order (instead of per item). The question didn't say $25.45 "each unit". After discussing "the goods", it says "their total was 20.34", suggesting that we've already added (to handle quantities), and are looking at the more final totals.
– TOOGAM
Jun 5 '17 at 2:07
|
show 1 more comment
up vote
3
down vote
The trouble with percentages (and a major source of math anxiety when people are doing mental arithmetic) is that they are inherently ambiguous. The question most people are not trained to ask is percent of what. Most of the problems occur because when percentages are use the percent of what is not explicitly specified.
In this question a 20% discount probably means deduct 20% from the stated price. But, unless this is stated very explicitly there is still room for confusion. If it really is 20% off the stated price then the correct result is price*0.8.
But it is a little ambiguous. Here is an example. In the UK we have a sales tax called VAT levied at 20%. But 20% of what? Legally it is 20% of the pre-tax price but shops have to quote the total price after tax has been applied (something the USA ought to mandate to avoid confusion for foreigners if not locals as well). So if a discount is described as "we pay your VAT" it sounds like a 20% discount to many but is actually a reduction of ~16.7% on the stated price (1/1.2 since the stated price is pre-tax price*1.2).
So, if you want to avoid confusion with percentages, always ask percent of what?
And, if you are going to be a good scientist always specify explicitly what your percentages mean. If your drug "reduces deaths by 20%" be very explicit in saying from what base (and tell us what percentage of people die without the drug so we can judge the absolute risk: 10 deaths reduced to 8 is a significant result when only 100 people were in the trial but not much when there are 10,000 people in the trial).
add a comment |
up vote
3
down vote
The trouble with percentages (and a major source of math anxiety when people are doing mental arithmetic) is that they are inherently ambiguous. The question most people are not trained to ask is percent of what. Most of the problems occur because when percentages are use the percent of what is not explicitly specified.
In this question a 20% discount probably means deduct 20% from the stated price. But, unless this is stated very explicitly there is still room for confusion. If it really is 20% off the stated price then the correct result is price*0.8.
But it is a little ambiguous. Here is an example. In the UK we have a sales tax called VAT levied at 20%. But 20% of what? Legally it is 20% of the pre-tax price but shops have to quote the total price after tax has been applied (something the USA ought to mandate to avoid confusion for foreigners if not locals as well). So if a discount is described as "we pay your VAT" it sounds like a 20% discount to many but is actually a reduction of ~16.7% on the stated price (1/1.2 since the stated price is pre-tax price*1.2).
So, if you want to avoid confusion with percentages, always ask percent of what?
And, if you are going to be a good scientist always specify explicitly what your percentages mean. If your drug "reduces deaths by 20%" be very explicit in saying from what base (and tell us what percentage of people die without the drug so we can judge the absolute risk: 10 deaths reduced to 8 is a significant result when only 100 people were in the trial but not much when there are 10,000 people in the trial).
add a comment |
up vote
3
down vote
up vote
3
down vote
The trouble with percentages (and a major source of math anxiety when people are doing mental arithmetic) is that they are inherently ambiguous. The question most people are not trained to ask is percent of what. Most of the problems occur because when percentages are use the percent of what is not explicitly specified.
In this question a 20% discount probably means deduct 20% from the stated price. But, unless this is stated very explicitly there is still room for confusion. If it really is 20% off the stated price then the correct result is price*0.8.
But it is a little ambiguous. Here is an example. In the UK we have a sales tax called VAT levied at 20%. But 20% of what? Legally it is 20% of the pre-tax price but shops have to quote the total price after tax has been applied (something the USA ought to mandate to avoid confusion for foreigners if not locals as well). So if a discount is described as "we pay your VAT" it sounds like a 20% discount to many but is actually a reduction of ~16.7% on the stated price (1/1.2 since the stated price is pre-tax price*1.2).
So, if you want to avoid confusion with percentages, always ask percent of what?
And, if you are going to be a good scientist always specify explicitly what your percentages mean. If your drug "reduces deaths by 20%" be very explicit in saying from what base (and tell us what percentage of people die without the drug so we can judge the absolute risk: 10 deaths reduced to 8 is a significant result when only 100 people were in the trial but not much when there are 10,000 people in the trial).
The trouble with percentages (and a major source of math anxiety when people are doing mental arithmetic) is that they are inherently ambiguous. The question most people are not trained to ask is percent of what. Most of the problems occur because when percentages are use the percent of what is not explicitly specified.
In this question a 20% discount probably means deduct 20% from the stated price. But, unless this is stated very explicitly there is still room for confusion. If it really is 20% off the stated price then the correct result is price*0.8.
But it is a little ambiguous. Here is an example. In the UK we have a sales tax called VAT levied at 20%. But 20% of what? Legally it is 20% of the pre-tax price but shops have to quote the total price after tax has been applied (something the USA ought to mandate to avoid confusion for foreigners if not locals as well). So if a discount is described as "we pay your VAT" it sounds like a 20% discount to many but is actually a reduction of ~16.7% on the stated price (1/1.2 since the stated price is pre-tax price*1.2).
So, if you want to avoid confusion with percentages, always ask percent of what?
And, if you are going to be a good scientist always specify explicitly what your percentages mean. If your drug "reduces deaths by 20%" be very explicit in saying from what base (and tell us what percentage of people die without the drug so we can judge the absolute risk: 10 deaths reduced to 8 is a significant result when only 100 people were in the trial but not much when there are 10,000 people in the trial).
answered Jun 4 '17 at 10:34
matt_black
20315
20315
add a comment |
add a comment |
up vote
0
down vote
You cannot multiply anything by 0.8333 to arrive at 80% of the original. All you end up with is 83.33% of the original. So to get a discount of 20%, you need to calculate 80% 0f that figure. Don't know where '.8333' came from! That only gives a discount of 16.7%. X times 0.8 does it right. To get that discounted figure back to its original, multiply by 1.25.
Please explain why you thought 0.8333 was a good idea, and also edit the question with one start point value - you wrote two different ones.
Basic answer, the 'less 20%' - aka times 0.8 can be the only way. Even if tax was applied to the item before and after discount, it would make no difference.
We have phantom downvoters on this site too! I need to know what the reason is, please!
– Tim
Jun 4 '17 at 16:44
1
I didn't downvote, though my guess would be that downvoters didn't feel that this answer added anything beyond what's already been covered in prior answers. Repetition makes for clutter and consumes readers' time for no return. You'd probably have gotten a lot of upvotes if this were the first answer.
– Nat
Jun 4 '17 at 21:53
add a comment |
up vote
0
down vote
You cannot multiply anything by 0.8333 to arrive at 80% of the original. All you end up with is 83.33% of the original. So to get a discount of 20%, you need to calculate 80% 0f that figure. Don't know where '.8333' came from! That only gives a discount of 16.7%. X times 0.8 does it right. To get that discounted figure back to its original, multiply by 1.25.
Please explain why you thought 0.8333 was a good idea, and also edit the question with one start point value - you wrote two different ones.
Basic answer, the 'less 20%' - aka times 0.8 can be the only way. Even if tax was applied to the item before and after discount, it would make no difference.
We have phantom downvoters on this site too! I need to know what the reason is, please!
– Tim
Jun 4 '17 at 16:44
1
I didn't downvote, though my guess would be that downvoters didn't feel that this answer added anything beyond what's already been covered in prior answers. Repetition makes for clutter and consumes readers' time for no return. You'd probably have gotten a lot of upvotes if this were the first answer.
– Nat
Jun 4 '17 at 21:53
add a comment |
up vote
0
down vote
up vote
0
down vote
You cannot multiply anything by 0.8333 to arrive at 80% of the original. All you end up with is 83.33% of the original. So to get a discount of 20%, you need to calculate 80% 0f that figure. Don't know where '.8333' came from! That only gives a discount of 16.7%. X times 0.8 does it right. To get that discounted figure back to its original, multiply by 1.25.
Please explain why you thought 0.8333 was a good idea, and also edit the question with one start point value - you wrote two different ones.
Basic answer, the 'less 20%' - aka times 0.8 can be the only way. Even if tax was applied to the item before and after discount, it would make no difference.
You cannot multiply anything by 0.8333 to arrive at 80% of the original. All you end up with is 83.33% of the original. So to get a discount of 20%, you need to calculate 80% 0f that figure. Don't know where '.8333' came from! That only gives a discount of 16.7%. X times 0.8 does it right. To get that discounted figure back to its original, multiply by 1.25.
Please explain why you thought 0.8333 was a good idea, and also edit the question with one start point value - you wrote two different ones.
Basic answer, the 'less 20%' - aka times 0.8 can be the only way. Even if tax was applied to the item before and after discount, it would make no difference.
answered Jun 4 '17 at 12:37
Tim
1094
1094
We have phantom downvoters on this site too! I need to know what the reason is, please!
– Tim
Jun 4 '17 at 16:44
1
I didn't downvote, though my guess would be that downvoters didn't feel that this answer added anything beyond what's already been covered in prior answers. Repetition makes for clutter and consumes readers' time for no return. You'd probably have gotten a lot of upvotes if this were the first answer.
– Nat
Jun 4 '17 at 21:53
add a comment |
We have phantom downvoters on this site too! I need to know what the reason is, please!
– Tim
Jun 4 '17 at 16:44
1
I didn't downvote, though my guess would be that downvoters didn't feel that this answer added anything beyond what's already been covered in prior answers. Repetition makes for clutter and consumes readers' time for no return. You'd probably have gotten a lot of upvotes if this were the first answer.
– Nat
Jun 4 '17 at 21:53
We have phantom downvoters on this site too! I need to know what the reason is, please!
– Tim
Jun 4 '17 at 16:44
We have phantom downvoters on this site too! I need to know what the reason is, please!
– Tim
Jun 4 '17 at 16:44
1
1
I didn't downvote, though my guess would be that downvoters didn't feel that this answer added anything beyond what's already been covered in prior answers. Repetition makes for clutter and consumes readers' time for no return. You'd probably have gotten a lot of upvotes if this were the first answer.
– Nat
Jun 4 '17 at 21:53
I didn't downvote, though my guess would be that downvoters didn't feel that this answer added anything beyond what's already been covered in prior answers. Repetition makes for clutter and consumes readers' time for no return. You'd probably have gotten a lot of upvotes if this were the first answer.
– Nat
Jun 4 '17 at 21:53
add a comment |
Thanks for contributing an answer to Mathematics Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Some of your past answers have not been well-received, and you're in danger of being blocked from answering.
Please pay close attention to the following guidance:
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2307126%2fcalculating-a-20-discount-by-multiplying-by-0-8333%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
2
$25.42times (1 - 20/100)$
– Éric Guirbal
Jun 2 '17 at 15:58
37
why multiply by $5/6$?
– Dando18
Jun 2 '17 at 16:00
11
You tell us neither where the $25.45$ comes from, nor the $0.8333$.
– Carsten S
Jun 2 '17 at 17:39
25
@CarstenS It's blatantly obvious that the 25.45 is the original price of the goods...
– The Great Duck
Jun 2 '17 at 20:24
11
Care to check your figures. You quote 25.45 then 25.42. Can't both be accurate.
– Tim
Jun 3 '17 at 14:16