-93.73% is the change from 638 to 40
Calculation steps:
[( 40 - 638 ) ÷ 638] x 100 = -93.73%
Formula
Percentage change = [(40 - 638) / 638] x 100
Subtract the new number by the original number
40 - 638 = -598
-598 ÷ 638 = -0.9373040752351097
-0.9373040752351097 x 100 = -93.73%