Percentages
Change needed to undo a prior change
Swap the roles: to return to the starting point, the base becomes the current value. Equivalent to x/(1+x) in magnitude.
The Formula
Required Change = (Original - New) / New x 100
Swap the roles: to return to the starting point, the base becomes the current value. Equivalent to x/(1+x) in magnitude.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| %Delta(reverse) | Change required to get back to the start | percent | Always smaller in magnitude than the original gain, and always larger when recovering from a loss. |
What Each Symbol Means
%Delta(reverse)percent
Change required to get back to the start
Always smaller in magnitude than the original gain, and always larger when recovering from a loss.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate percentage change page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate Percentage Change, filed under Math. Every number the guide produces comes from substituting into this one line.