21.09% is the change from 512 to 620
Calculation steps:
[( 620 - 512 ) ÷ 512] x 100 = 21.09%
Formula
Percentage change = [(620 - 512) / 512] x 100
Subtract the new number by the original number
620 - 512 = 108
108 ÷ 512 = 0.2109375
0.2109375 x 100 = 21.09%