2938.1% is the change from 21 to 638
Calculation steps:
[( 638 - 21 ) ÷ 21] x 100 = 2938.1%
Formula
Percentage change = [(638 - 21) / 21] x 100
Subtract the new number by the original number
638 - 21 = 617
617 ÷ 21 = 29.38095238095238
29.38095238095238 x 100 = 2938.1%