-91.82% is the change from 990 to 81
Calculation steps:
[( 81 - 990 ) ÷ 990] x 100 = -91.82%
Formula
Percentage change = [(81 - 990) / 990] x 100
Subtract the new number by the original number
81 - 990 = -909
-909 ÷ 990 = -0.9181818181818182
-0.9181818181818182 x 100 = -91.82%