-96.72% is the change from 641 to 21
Calculation steps:
[( 21 - 641 ) ÷ 641] x 100 = -96.72%
Formula
Percentage change = [(21 - 641) / 641] x 100
Subtract the new number by the original number
21 - 641 = -620
-620 ÷ 641 = -0.9672386895475819
-0.9672386895475819 x 100 = -96.72%