-21.63% is the change from 638 to 500
Calculation steps:
[( 500 - 638 ) ÷ 638] x 100 = -21.63%
Formula
Percentage change = [(500 - 638) / 638] x 100
Subtract the new number by the original number
500 - 638 = -138
-138 ÷ 638 = -0.21630094043887146
-0.21630094043887146 x 100 = -21.63%