-50.62% is the change from 81 to 40
Calculation steps:
[( 40 - 81 ) ÷ 81] x 100 = -50.62%
Formula
Percentage change = [(40 - 81) / 81] x 100
Subtract the new number by the original number
40 - 81 = -41
-41 ÷ 81 = -0.5061728395061729
-0.5061728395061729 x 100 = -50.62%