-19.57% is the change from 828 to 666
Calculation steps:
[( 666 - 828 ) ÷ 828] x 100 = -19.57%
Formula
Percentage change = [(666 - 828) / 828] x 100
Subtract the new number by the original number
666 - 828 = -162
-162 ÷ 828 = -0.1956521739130435
-0.1956521739130435 x 100 = -19.57%