-87.36% is the change from 641 to 81
Calculation steps:
[( 81 - 641 ) ÷ 641] x 100 = -87.36%
Formula
Percentage change = [(81 - 641) / 641] x 100
Subtract the new number by the original number
81 - 641 = -560
-560 ÷ 641 = -0.8736349453978159
-0.8736349453978159 x 100 = -87.36%