-96.74% is the change from 644 to 21
Calculation steps:
[( 21 - 644 ) ÷ 644] x 100 = -96.74%
Formula
Percentage change = [(21 - 644) / 644] x 100
Subtract the new number by the original number
21 - 644 = -623
-623 ÷ 644 = -0.967391304347826
-0.967391304347826 x 100 = -96.74%