-25.31% is the change from 640 to 478
Calculation steps:
[( 478 - 640 ) ÷ 640] x 100 = -25.31%
Formula
Percentage change = [(478 - 640) / 640] x 100
Subtract the new number by the original number
478 - 640 = -162
-162 ÷ 640 = -0.253125
-0.253125 x 100 = -25.31%