-21.43% is the change from 812 to 638
Calculation steps:
[( 638 - 812 ) ÷ 812] x 100 = -21.43%
Formula
Percentage change = [(638 - 812) / 812] x 100
Subtract the new number by the original number
638 - 812 = -174
-174 ÷ 812 = -0.21428571428571427
-0.21428571428571427 x 100 = -21.43%