-96.87% is the change from 638 to 20
Calculation steps:
[( 20 - 638 ) ÷ 638] x 100 = -96.87%
Formula
Percentage change = [(20 - 638) / 638] x 100
Subtract the new number by the original number
20 - 638 = -618
-618 ÷ 638 = -0.9686520376175548
-0.9686520376175548 x 100 = -96.87%