Percentages
New value after a known percent decrease
The forward form. Multiply the original by the share that survives: a 25% decrease keeps the factor 0.75.
The Formula
New = Original x (1 - p)
The forward form. Multiply the original by the share that survives: a 25% decrease keeps the factor 0.75.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| p | Decrease written as a decimal | decimal | 25.00% enters as 0.25, so the surviving factor is 0.75. |
| V0 | Original value | number | What you started from; 120 in the standard worked case. |
| V1 | Value after the decrease | number | 120 x 0.75 = 90, which is the same fact stated multiplicatively. |
What Each Symbol Means
pdecimal
Decrease written as a decimal
25.00% enters as 0.25, so the surviving factor is 0.75.
V0number
Original value
What you started from; 120 in the standard worked case.
V1number
Value after the decrease
120 x 0.75 = 90, which is the same fact stated multiplicatively.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate percent decrease 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 Percent Decrease, filed under Math. Every number the guide produces comes from substituting into this one line.