-97.58% is the change from 621 to 15
Calculation steps:
[( 15 - 621 ) ÷ 621] x 100 = -97.58%
Formula
Percentage change = [(15 - 621) / 621] x 100
Subtract the new number by the original number
15 - 621 = -606
-606 ÷ 621 = -0.9758454106280193
-0.9758454106280193 x 100 = -97.58%