3120% is the change from 20 to 644
Calculation steps:
[( 644 - 20 ) ÷ 20] x 100 = 3120%
Formula
Percentage change = [(644 - 20) / 20] x 100
Subtract the new number by the original number
644 - 20 = 624
624 ÷ 20 = 31.2
31.2 x 100 = 3120%
Example