-0.24% is the change from 817 to 815
Calculation steps:
[( 815 - 817 ) ÷ 817] x 100 = -0.24%
Formula
Percentage change = [(815 - 817) / 817] x 100
Subtract the new number by the original number
815 - 817 = -2
-2 ÷ 817 = -0.0024479804161566705
-0.0024479804161566705 x 100 = -0.24%