307.03% is the change from 128 to 521
Calculation steps:
[( 521 - 128 ) ÷ 128] x 100 = 307.03%
Formula
Percentage change = [(521 - 128) / 128] x 100
Subtract the new number by the original number
521 - 128 = 393
393 ÷ 128 = 3.0703125
3.0703125 x 100 = 307.03%