300% is the change from 64 to 256
Calculation steps:
[( 256 - 64 ) ÷ 64] x 100 = 300%
Formula
Percentage change = [(256 - 64) / 64] x 100
Subtract the new number by the original number
256 - 64 = 192
192 ÷ 64 = 3
3 x 100 = 300%
Example