309.6% is the change from 125 to 512
Calculation steps:
[( 512 - 125 ) ÷ 125] x 100 = 309.6%
Formula
Percentage change = [(512 - 125) / 125] x 100
Subtract the new number by the original number
512 - 125 = 387
387 ÷ 125 = 3.096
3.096 x 100 = 309.6%
Example