-96.9% is the change from 645 to 20
Calculation steps:
[( 20 - 645 ) ÷ 645] x 100 = -96.9%
Formula
Percentage change = [(20 - 645) / 645] x 100
Subtract the new number by the original number
20 - 645 = -625
-625 ÷ 645 = -0.9689922480620154
-0.9689922480620154 x 100 = -96.9%