-86.5% is the change from 600 to 81
Calculation steps:
[( 81 - 600 ) ÷ 600] x 100 = -86.5%
Formula
Percentage change = [(81 - 600) / 600] x 100
Subtract the new number by the original number
81 - 600 = -519
-519 ÷ 600 = -0.865
-0.865 x 100 = -86.5%
Example