-1.57% is the change from 828 to 815
Calculation steps:
[( 815 - 828 ) ÷ 828] x 100 = -1.57%
Formula
Percentage change = [(815 - 828) / 828] x 100
Subtract the new number by the original number
815 - 828 = -13
-13 ÷ 828 = -0.01570048309178744
-0.01570048309178744 x 100 = -1.57%