-96.87% is the change from 671 to 21
Calculation steps:
[( 21 - 671 ) ÷ 671] x 100 = -96.87%
Formula
Percentage change = [(21 - 671) / 671] x 100
Subtract the new number by the original number
21 - 671 = -650
-650 ÷ 671 = -0.9687034277198212
-0.9687034277198212 x 100 = -96.87%