Check the change with a multiplier
The ratio of the new value to the starting value is 0.8. Comparing that multiplier with 1 shows how far the new value sits below the starting value in percentage terms.
- 1.New ÷ original = 200 ÷ 250 = 0.8.
- 2.Subtract 1: 0.8 − 1 = -0.2.
- 3.Multiply by 100 to get 20% decrease.