64.06% is the change from 256 to 420
Calculation steps:
[( 420 - 256 ) ÷ 256] x 100 = 64.06%
Formula
Percentage change = [(420 - 256) / 256] x 100
Subtract the new number by the original number
420 - 256 = 164
164 ÷ 256 = 0.640625
0.640625 x 100 = 64.06%