7900% is the change from 8 to 640
Calculation steps:
[( 640 - 8 ) ÷ 8] x 100 = 7900%
Formula
Percentage change = [(640 - 8) / 8] x 100
Subtract the new number by the original number
640 - 8 = 632
632 ÷ 8 = 79
79 x 100 = 7900%
Example