-81.72% is the change from 640 to 117
Calculation steps:
[( 117 - 640 ) ÷ 640] x 100 = -81.72%
Formula
Percentage change = [(117 - 640) / 640] x 100
Subtract the new number by the original number
117 - 640 = -523
-523 ÷ 640 = -0.8171875
-0.8171875 x 100 = -81.72%