-55.31% is the change from 640 to 286
Calculation steps:
[( 286 - 640 ) ÷ 640] x 100 = -55.31%
Formula
Percentage change = [(286 - 640) / 640] x 100
Subtract the new number by the original number
286 - 640 = -354
-354 ÷ 640 = -0.553125
-0.553125 x 100 = -55.31%