-75.63% is the change from 640 to 156
Calculation steps:
[( 156 - 640 ) ÷ 640] x 100 = -75.63%
Formula
Percentage change = [(156 - 640) / 640] x 100
Subtract the new number by the original number
156 - 640 = -484
-484 ÷ 640 = -0.75625
-0.75625 x 100 = -75.63%