-20.94% is the change from 812 to 642
Calculation steps:
[( 642 - 812 ) ÷ 812] x 100 = -20.94%
Formula
Percentage change = [(642 - 812) / 812] x 100
Subtract the new number by the original number
642 - 812 = -170
-170 ÷ 812 = -0.20935960591133004
-0.20935960591133004 x 100 = -20.94%