-98.91% is the change from 640 to 7
Calculation steps:
[( 7 - 640 ) ÷ 640] x 100 = -98.91%
Formula
Percentage change = [(7 - 640) / 640] x 100
Subtract the new number by the original number
7 - 640 = -633
-633 ÷ 640 = -0.9890625
-0.9890625 x 100 = -98.91%