-21.07% is the change from 636 to 502
Calculation steps:
[( 502 - 636 ) ÷ 636] x 100 = -21.07%
Formula
Percentage change = [(502 - 636) / 636] x 100
Subtract the new number by the original number
502 - 636 = -134
-134 ÷ 636 = -0.21069182389937108
-0.21069182389937108 x 100 = -21.07%