-63.13% is the change from 640 to 236
Calculation steps:
[( 236 - 640 ) ÷ 640] x 100 = -63.13%
Formula
Percentage change = [(236 - 640) / 640] x 100
Subtract the new number by the original number
236 - 640 = -404
-404 ÷ 640 = -0.63125
-0.63125 x 100 = -63.13%