0.16% is the change from 640 to 641
Calculation steps:
[( 641 - 640 ) ÷ 640] x 100 = 0.16%
Formula
Percentage change = [(641 - 640) / 640] x 100
Subtract the new number by the original number
641 - 640 = 1
1 ÷ 640 = 0.0015625
0.0015625 x 100 = 0.16%
Example