-83.83% is the change from 501 to 81
Calculation steps:
[( 81 - 501 ) ÷ 501] x 100 = -83.83%
Formula
Percentage change = [(81 - 501) / 501] x 100
Subtract the new number by the original number
81 - 501 = -420
-420 ÷ 501 = -0.8383233532934131
-0.8383233532934131 x 100 = -83.83%