-21.68% is the change from 641 to 502
Calculation steps:
[( 502 - 641 ) ÷ 641] x 100 = -21.68%
Formula
Percentage change = [(502 - 641) / 641] x 100
Subtract the new number by the original number
502 - 641 = -139
-139 ÷ 641 = -0.21684867394695787
-0.21684867394695787 x 100 = -21.68%