Percentual change from 0











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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?










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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















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?










share|cite|improve this question
























  • 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













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?










share|cite|improve this question















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






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








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


















  • 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










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.






share|cite|improve this answer





















  • "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


















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.






share|cite|improve this answer





















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    2 Answers
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    2 Answers
    2






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    active

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    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.






    share|cite|improve this answer





















    • "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















    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.






    share|cite|improve this answer





















    • "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













    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.






    share|cite|improve this answer












    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.







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    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


















    • "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










    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.






    share|cite|improve this answer

























      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.






      share|cite|improve this answer























        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.






        share|cite|improve this answer












        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.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 6 at 8:28









        Eevee Trainer

        2,551221




        2,551221






























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