-98.28% is the change from 640 to 11
Calculation steps:
[( 11 - 640 ) ÷ 640] x 100 = -98.28%
Formula
Percentage change = [(11 - 640) / 640] x 100
Subtract the new number by the original number
11 - 640 = -629
-629 ÷ 640 = -0.9828125
-0.9828125 x 100 = -98.28%