-81.03% is the change from 638 to 121
Calculation steps:
[( 121 - 638 ) ÷ 638] x 100 = -81.03%
Formula
Percentage change = [(121 - 638) / 638] x 100
Subtract the new number by the original number
121 - 638 = -517
-517 ÷ 638 = -0.8103448275862069
-0.8103448275862069 x 100 = -81.03%