-90.23% is the change from 829 to 81
Calculation steps:
[( 81 - 829 ) ÷ 829] x 100 = -90.23%
Formula
Percentage change = [(81 - 829) / 829] x 100
Subtract the new number by the original number
81 - 829 = -748
-748 ÷ 829 = -0.902291917973462
-0.902291917973462 x 100 = -90.23%