64.45% is the change from 256 to 421
Calculation steps:
[( 421 - 256 ) ÷ 256] x 100 = 64.45%
Formula
Percentage change = [(421 - 256) / 256] x 100
Subtract the new number by the original number
421 - 256 = 165
165 ÷ 256 = 0.64453125
0.64453125 x 100 = 64.45%