-89.88% is the change from 800 to 81
Calculation steps:
[( 81 - 800 ) ÷ 800] x 100 = -89.88%
Formula
Percentage change = [(81 - 800) / 800] x 100
Subtract the new number by the original number
81 - 800 = -719
-719 ÷ 800 = -0.89875
-0.89875 x 100 = -89.88%