3090.48% is the change from 21 to 670
Calculation steps:
[( 670 - 21 ) ÷ 21] x 100 = 3090.48%
Formula
Percentage change = [(670 - 21) / 21] x 100
Subtract the new number by the original number
670 - 21 = 649
649 ÷ 21 = 30.904761904761905
30.904761904761905 x 100 = 3090.48%