-24.39% is the change from 820 to 620
Calculation steps:
[( 620 - 820 ) ÷ 820] x 100 = -24.39%
Formula
Percentage change = [(620 - 820) / 820] x 100
Subtract the new number by the original number
620 - 820 = -200
-200 ÷ 820 = -0.24390243902439024
-0.24390243902439024 x 100 = -24.39%