-20.81% is the change from 817 to 647
Calculation steps:
[( 647 - 817 ) ÷ 817] x 100 = -20.81%
Formula
Percentage change = [(647 - 817) / 817] x 100
Subtract the new number by the original number
647 - 817 = -170
-170 ÷ 817 = -0.20807833537331702
-0.20807833537331702 x 100 = -20.81%