-16.09% is the change from 640 to 537
Calculation steps:
[( 537 - 640 ) ÷ 640] x 100 = -16.09%
Formula
Percentage change = [(537 - 640) / 640] x 100
Subtract the new number by the original number
537 - 640 = -103
-103 ÷ 640 = -0.1609375
-0.1609375 x 100 = -16.09%