-96.88% is the change from 641 to 20
Calculation steps:
[( 20 - 641 ) ÷ 641] x 100 = -96.88%
Formula
Percentage change = [(20 - 641) / 641] x 100
Subtract the new number by the original number
20 - 641 = -621
-621 ÷ 641 = -0.968798751950078
-0.968798751950078 x 100 = -96.88%