-90.11% is the change from 819 to 81
Calculation steps:
[( 81 - 819 ) ÷ 819] x 100 = -90.11%
Formula
Percentage change = [(81 - 819) / 819] x 100
Subtract the new number by the original number
81 - 819 = -738
-738 ÷ 819 = -0.9010989010989011
-0.9010989010989011 x 100 = -90.11%