-0.24% is the change from 823 to 821
Calculation steps:
[( 821 - 823 ) ÷ 823] x 100 = -0.24%
Formula
Percentage change = [(821 - 823) / 823] x 100
Subtract the new number by the original number
821 - 823 = -2
-2 ÷ 823 = -0.002430133657351154
-0.002430133657351154 x 100 = -0.24%