-23.91% is the change from 640 to 487
Calculation steps:
[( 487 - 640 ) ÷ 640] x 100 = -23.91%
Formula
Percentage change = [(487 - 640) / 640] x 100
Subtract the new number by the original number
487 - 640 = -153
-153 ÷ 640 = -0.2390625
-0.2390625 x 100 = -23.91%