-95.8% is the change from 500 to 21
Calculation steps:
[( 21 - 500 ) ÷ 500] x 100 = -95.8%
Formula
Percentage change = [(21 - 500) / 500] x 100
Subtract the new number by the original number
21 - 500 = -479
-479 ÷ 500 = -0.958
-0.958 x 100 = -95.8%
Example