Percentual change from 0
up vote
0
down vote
favorite
How to calculate the procentual change with respect to 0.
For example: The old value is 0, while the new value is 10.
How to calculate the procentual change in this case?
average
add a comment |
up vote
0
down vote
favorite
How to calculate the procentual change with respect to 0.
For example: The old value is 0, while the new value is 10.
How to calculate the procentual change in this case?
average
Isn't it always $100$% since the previous number is $0$? Edit: Oh, too late
– NotEinstein
Dec 6 at 7:50
1
It's undefined. There can be no relative change from $0$. The absolute change is $10$ ($10-0 = 10$).
– Eff
Dec 6 at 8:31
(I forgot about the initial value in my previous comment, so here’s the correction.) $frac{v_2-v_1}{v_1}$ is undefined for $v_1 = 0$. If you have $v_1 = 2$ and $v_2 = 3$, for instance, you get a percentage change of $50$%. In other words, $2$ added to $50$% of itself gives $3$. Can $0$ added to any percentage of itself give a non-zero number?
– KM101
Dec 6 at 8:41
The "percentage change" number isn't that useful when your number is hovering around zero anyway.
– James
Dec 6 at 13:44
add a comment |
up vote
0
down vote
favorite
up vote
0
down vote
favorite
How to calculate the procentual change with respect to 0.
For example: The old value is 0, while the new value is 10.
How to calculate the procentual change in this case?
average
How to calculate the procentual change with respect to 0.
For example: The old value is 0, while the new value is 10.
How to calculate the procentual change in this case?
average
average
edited Dec 6 at 9:15
nippon
335212
335212
asked Dec 6 at 7:46
Abhijit Bendigiri
71
71
Isn't it always $100$% since the previous number is $0$? Edit: Oh, too late
– NotEinstein
Dec 6 at 7:50
1
It's undefined. There can be no relative change from $0$. The absolute change is $10$ ($10-0 = 10$).
– Eff
Dec 6 at 8:31
(I forgot about the initial value in my previous comment, so here’s the correction.) $frac{v_2-v_1}{v_1}$ is undefined for $v_1 = 0$. If you have $v_1 = 2$ and $v_2 = 3$, for instance, you get a percentage change of $50$%. In other words, $2$ added to $50$% of itself gives $3$. Can $0$ added to any percentage of itself give a non-zero number?
– KM101
Dec 6 at 8:41
The "percentage change" number isn't that useful when your number is hovering around zero anyway.
– James
Dec 6 at 13:44
add a comment |
Isn't it always $100$% since the previous number is $0$? Edit: Oh, too late
– NotEinstein
Dec 6 at 7:50
1
It's undefined. There can be no relative change from $0$. The absolute change is $10$ ($10-0 = 10$).
– Eff
Dec 6 at 8:31
(I forgot about the initial value in my previous comment, so here’s the correction.) $frac{v_2-v_1}{v_1}$ is undefined for $v_1 = 0$. If you have $v_1 = 2$ and $v_2 = 3$, for instance, you get a percentage change of $50$%. In other words, $2$ added to $50$% of itself gives $3$. Can $0$ added to any percentage of itself give a non-zero number?
– KM101
Dec 6 at 8:41
The "percentage change" number isn't that useful when your number is hovering around zero anyway.
– James
Dec 6 at 13:44
Isn't it always $100$% since the previous number is $0$? Edit: Oh, too late
– NotEinstein
Dec 6 at 7:50
Isn't it always $100$% since the previous number is $0$? Edit: Oh, too late
– NotEinstein
Dec 6 at 7:50
1
1
It's undefined. There can be no relative change from $0$. The absolute change is $10$ ($10-0 = 10$).
– Eff
Dec 6 at 8:31
It's undefined. There can be no relative change from $0$. The absolute change is $10$ ($10-0 = 10$).
– Eff
Dec 6 at 8:31
(I forgot about the initial value in my previous comment, so here’s the correction.) $frac{v_2-v_1}{v_1}$ is undefined for $v_1 = 0$. If you have $v_1 = 2$ and $v_2 = 3$, for instance, you get a percentage change of $50$%. In other words, $2$ added to $50$% of itself gives $3$. Can $0$ added to any percentage of itself give a non-zero number?
– KM101
Dec 6 at 8:41
(I forgot about the initial value in my previous comment, so here’s the correction.) $frac{v_2-v_1}{v_1}$ is undefined for $v_1 = 0$. If you have $v_1 = 2$ and $v_2 = 3$, for instance, you get a percentage change of $50$%. In other words, $2$ added to $50$% of itself gives $3$. Can $0$ added to any percentage of itself give a non-zero number?
– KM101
Dec 6 at 8:41
The "percentage change" number isn't that useful when your number is hovering around zero anyway.
– James
Dec 6 at 13:44
The "percentage change" number isn't that useful when your number is hovering around zero anyway.
– James
Dec 6 at 13:44
add a comment |
2 Answers
2
active
oldest
votes
up vote
5
down vote
When the previous value $x$ is non-zero, the formula is $$frac{y-x}{x} times 100 %$$
Now, remember that we are not supposed to divide by $0$.
It should be undefined.
If it is defined and we claim that it is $r$, a real number, given the percentage change and the current value, we can't recover $x$ to be $0$ and we might misguide ourselves to think that $x$ is some non-zero number.
$$frac{y}x =1+frac{r}{100}$$
$$x=frac{y}{1+frac{r}{100}}$$
If you have to put down something, perhaps put down a symbol to indicate that the previous number is zero.
"perhaps put down a symbol to..." - and I'd suggest to use the symbol ∞. Just remember that this is not a number, it's just a symbol that indicated the previous number is zero. Which should be clear to a mathematician, but perhaps not to a casual reader.
– Radovan Garabík
Dec 6 at 14:27
add a comment |
up vote
4
down vote
While the other answer by Siong Thye Goh is right, I want to present a slightly more intuitive approach.
The "percent change" of $x$ to $y$ is essentially saying, for some number $p$,
$$x + (p% text{ of } x) = y$$
For example, the percentage change of $2$ to $5$ can be calculated via the method Siong mentioned:
$$frac{5-2}{2} times 100% = frac{3}{2} times 100% = 150%$$
We can equivalently state what this means by
$$2 + (150% text{ of } 2) = 5$$
Since $150%$ of $2$ is given by $150% cdot 2 = 1.5 cdot 2 = 3$, this idea becomes somewhat clear, this idea being that
$$x + (p% text{ of } x) = y ;;; Leftrightarrow ;;; frac{y-x}{x} = p$$
i.e. this intuitive approach is analogous to the formula you usually get told a la what Siong noted.
So we ask: what if $x = 0$, and $y neq 0$? Well, we have
$$0 + (p% text{ of } 0) = y neq 0$$
Okay, but $0$ plus anything is just that thing, and any percentage of $0$ is $0$, and $0+0=0$. Thus, we get
$$0 = y neq 0$$
i.e. a nonsensical answer, and our $p$ is irrelevant here. No matter what $p$ is, there is always this contradiction. Similarly, if $y=0$, then we get a true statement instead but it's true for all possible values of $p$ instead.
So in that sense, we say that the percentage change starting from $0$ is nonsensical. Either you have a contradictory answer or just a plain true statement, regardless of your $p$ - $p$ becomes irrelevant in both cases. So it only makes sense to say that the percentage change $p$ is undefined.
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
5
down vote
When the previous value $x$ is non-zero, the formula is $$frac{y-x}{x} times 100 %$$
Now, remember that we are not supposed to divide by $0$.
It should be undefined.
If it is defined and we claim that it is $r$, a real number, given the percentage change and the current value, we can't recover $x$ to be $0$ and we might misguide ourselves to think that $x$ is some non-zero number.
$$frac{y}x =1+frac{r}{100}$$
$$x=frac{y}{1+frac{r}{100}}$$
If you have to put down something, perhaps put down a symbol to indicate that the previous number is zero.
"perhaps put down a symbol to..." - and I'd suggest to use the symbol ∞. Just remember that this is not a number, it's just a symbol that indicated the previous number is zero. Which should be clear to a mathematician, but perhaps not to a casual reader.
– Radovan Garabík
Dec 6 at 14:27
add a comment |
up vote
5
down vote
When the previous value $x$ is non-zero, the formula is $$frac{y-x}{x} times 100 %$$
Now, remember that we are not supposed to divide by $0$.
It should be undefined.
If it is defined and we claim that it is $r$, a real number, given the percentage change and the current value, we can't recover $x$ to be $0$ and we might misguide ourselves to think that $x$ is some non-zero number.
$$frac{y}x =1+frac{r}{100}$$
$$x=frac{y}{1+frac{r}{100}}$$
If you have to put down something, perhaps put down a symbol to indicate that the previous number is zero.
"perhaps put down a symbol to..." - and I'd suggest to use the symbol ∞. Just remember that this is not a number, it's just a symbol that indicated the previous number is zero. Which should be clear to a mathematician, but perhaps not to a casual reader.
– Radovan Garabík
Dec 6 at 14:27
add a comment |
up vote
5
down vote
up vote
5
down vote
When the previous value $x$ is non-zero, the formula is $$frac{y-x}{x} times 100 %$$
Now, remember that we are not supposed to divide by $0$.
It should be undefined.
If it is defined and we claim that it is $r$, a real number, given the percentage change and the current value, we can't recover $x$ to be $0$ and we might misguide ourselves to think that $x$ is some non-zero number.
$$frac{y}x =1+frac{r}{100}$$
$$x=frac{y}{1+frac{r}{100}}$$
If you have to put down something, perhaps put down a symbol to indicate that the previous number is zero.
When the previous value $x$ is non-zero, the formula is $$frac{y-x}{x} times 100 %$$
Now, remember that we are not supposed to divide by $0$.
It should be undefined.
If it is defined and we claim that it is $r$, a real number, given the percentage change and the current value, we can't recover $x$ to be $0$ and we might misguide ourselves to think that $x$ is some non-zero number.
$$frac{y}x =1+frac{r}{100}$$
$$x=frac{y}{1+frac{r}{100}}$$
If you have to put down something, perhaps put down a symbol to indicate that the previous number is zero.
answered Dec 6 at 7:55
Siong Thye Goh
97.4k1463116
97.4k1463116
"perhaps put down a symbol to..." - and I'd suggest to use the symbol ∞. Just remember that this is not a number, it's just a symbol that indicated the previous number is zero. Which should be clear to a mathematician, but perhaps not to a casual reader.
– Radovan Garabík
Dec 6 at 14:27
add a comment |
"perhaps put down a symbol to..." - and I'd suggest to use the symbol ∞. Just remember that this is not a number, it's just a symbol that indicated the previous number is zero. Which should be clear to a mathematician, but perhaps not to a casual reader.
– Radovan Garabík
Dec 6 at 14:27
"perhaps put down a symbol to..." - and I'd suggest to use the symbol ∞. Just remember that this is not a number, it's just a symbol that indicated the previous number is zero. Which should be clear to a mathematician, but perhaps not to a casual reader.
– Radovan Garabík
Dec 6 at 14:27
"perhaps put down a symbol to..." - and I'd suggest to use the symbol ∞. Just remember that this is not a number, it's just a symbol that indicated the previous number is zero. Which should be clear to a mathematician, but perhaps not to a casual reader.
– Radovan Garabík
Dec 6 at 14:27
add a comment |
up vote
4
down vote
While the other answer by Siong Thye Goh is right, I want to present a slightly more intuitive approach.
The "percent change" of $x$ to $y$ is essentially saying, for some number $p$,
$$x + (p% text{ of } x) = y$$
For example, the percentage change of $2$ to $5$ can be calculated via the method Siong mentioned:
$$frac{5-2}{2} times 100% = frac{3}{2} times 100% = 150%$$
We can equivalently state what this means by
$$2 + (150% text{ of } 2) = 5$$
Since $150%$ of $2$ is given by $150% cdot 2 = 1.5 cdot 2 = 3$, this idea becomes somewhat clear, this idea being that
$$x + (p% text{ of } x) = y ;;; Leftrightarrow ;;; frac{y-x}{x} = p$$
i.e. this intuitive approach is analogous to the formula you usually get told a la what Siong noted.
So we ask: what if $x = 0$, and $y neq 0$? Well, we have
$$0 + (p% text{ of } 0) = y neq 0$$
Okay, but $0$ plus anything is just that thing, and any percentage of $0$ is $0$, and $0+0=0$. Thus, we get
$$0 = y neq 0$$
i.e. a nonsensical answer, and our $p$ is irrelevant here. No matter what $p$ is, there is always this contradiction. Similarly, if $y=0$, then we get a true statement instead but it's true for all possible values of $p$ instead.
So in that sense, we say that the percentage change starting from $0$ is nonsensical. Either you have a contradictory answer or just a plain true statement, regardless of your $p$ - $p$ becomes irrelevant in both cases. So it only makes sense to say that the percentage change $p$ is undefined.
add a comment |
up vote
4
down vote
While the other answer by Siong Thye Goh is right, I want to present a slightly more intuitive approach.
The "percent change" of $x$ to $y$ is essentially saying, for some number $p$,
$$x + (p% text{ of } x) = y$$
For example, the percentage change of $2$ to $5$ can be calculated via the method Siong mentioned:
$$frac{5-2}{2} times 100% = frac{3}{2} times 100% = 150%$$
We can equivalently state what this means by
$$2 + (150% text{ of } 2) = 5$$
Since $150%$ of $2$ is given by $150% cdot 2 = 1.5 cdot 2 = 3$, this idea becomes somewhat clear, this idea being that
$$x + (p% text{ of } x) = y ;;; Leftrightarrow ;;; frac{y-x}{x} = p$$
i.e. this intuitive approach is analogous to the formula you usually get told a la what Siong noted.
So we ask: what if $x = 0$, and $y neq 0$? Well, we have
$$0 + (p% text{ of } 0) = y neq 0$$
Okay, but $0$ plus anything is just that thing, and any percentage of $0$ is $0$, and $0+0=0$. Thus, we get
$$0 = y neq 0$$
i.e. a nonsensical answer, and our $p$ is irrelevant here. No matter what $p$ is, there is always this contradiction. Similarly, if $y=0$, then we get a true statement instead but it's true for all possible values of $p$ instead.
So in that sense, we say that the percentage change starting from $0$ is nonsensical. Either you have a contradictory answer or just a plain true statement, regardless of your $p$ - $p$ becomes irrelevant in both cases. So it only makes sense to say that the percentage change $p$ is undefined.
add a comment |
up vote
4
down vote
up vote
4
down vote
While the other answer by Siong Thye Goh is right, I want to present a slightly more intuitive approach.
The "percent change" of $x$ to $y$ is essentially saying, for some number $p$,
$$x + (p% text{ of } x) = y$$
For example, the percentage change of $2$ to $5$ can be calculated via the method Siong mentioned:
$$frac{5-2}{2} times 100% = frac{3}{2} times 100% = 150%$$
We can equivalently state what this means by
$$2 + (150% text{ of } 2) = 5$$
Since $150%$ of $2$ is given by $150% cdot 2 = 1.5 cdot 2 = 3$, this idea becomes somewhat clear, this idea being that
$$x + (p% text{ of } x) = y ;;; Leftrightarrow ;;; frac{y-x}{x} = p$$
i.e. this intuitive approach is analogous to the formula you usually get told a la what Siong noted.
So we ask: what if $x = 0$, and $y neq 0$? Well, we have
$$0 + (p% text{ of } 0) = y neq 0$$
Okay, but $0$ plus anything is just that thing, and any percentage of $0$ is $0$, and $0+0=0$. Thus, we get
$$0 = y neq 0$$
i.e. a nonsensical answer, and our $p$ is irrelevant here. No matter what $p$ is, there is always this contradiction. Similarly, if $y=0$, then we get a true statement instead but it's true for all possible values of $p$ instead.
So in that sense, we say that the percentage change starting from $0$ is nonsensical. Either you have a contradictory answer or just a plain true statement, regardless of your $p$ - $p$ becomes irrelevant in both cases. So it only makes sense to say that the percentage change $p$ is undefined.
While the other answer by Siong Thye Goh is right, I want to present a slightly more intuitive approach.
The "percent change" of $x$ to $y$ is essentially saying, for some number $p$,
$$x + (p% text{ of } x) = y$$
For example, the percentage change of $2$ to $5$ can be calculated via the method Siong mentioned:
$$frac{5-2}{2} times 100% = frac{3}{2} times 100% = 150%$$
We can equivalently state what this means by
$$2 + (150% text{ of } 2) = 5$$
Since $150%$ of $2$ is given by $150% cdot 2 = 1.5 cdot 2 = 3$, this idea becomes somewhat clear, this idea being that
$$x + (p% text{ of } x) = y ;;; Leftrightarrow ;;; frac{y-x}{x} = p$$
i.e. this intuitive approach is analogous to the formula you usually get told a la what Siong noted.
So we ask: what if $x = 0$, and $y neq 0$? Well, we have
$$0 + (p% text{ of } 0) = y neq 0$$
Okay, but $0$ plus anything is just that thing, and any percentage of $0$ is $0$, and $0+0=0$. Thus, we get
$$0 = y neq 0$$
i.e. a nonsensical answer, and our $p$ is irrelevant here. No matter what $p$ is, there is always this contradiction. Similarly, if $y=0$, then we get a true statement instead but it's true for all possible values of $p$ instead.
So in that sense, we say that the percentage change starting from $0$ is nonsensical. Either you have a contradictory answer or just a plain true statement, regardless of your $p$ - $p$ becomes irrelevant in both cases. So it only makes sense to say that the percentage change $p$ is undefined.
answered Dec 6 at 8:28
Eevee Trainer
2,551221
2,551221
add a comment |
add a comment |
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Isn't it always $100$% since the previous number is $0$? Edit: Oh, too late
– NotEinstein
Dec 6 at 7:50
1
It's undefined. There can be no relative change from $0$. The absolute change is $10$ ($10-0 = 10$).
– Eff
Dec 6 at 8:31
(I forgot about the initial value in my previous comment, so here’s the correction.) $frac{v_2-v_1}{v_1}$ is undefined for $v_1 = 0$. If you have $v_1 = 2$ and $v_2 = 3$, for instance, you get a percentage change of $50$%. In other words, $2$ added to $50$% of itself gives $3$. Can $0$ added to any percentage of itself give a non-zero number?
– KM101
Dec 6 at 8:41
The "percentage change" number isn't that useful when your number is hovering around zero anyway.
– James
Dec 6 at 13:44