200% is the change from 256 to 768
Calculation steps:
[( 768 - 256 ) ÷ 256] x 100 = 200%
Formula
Percentage change = [(768 - 256) / 256] x 100
Subtract the new number by the original number
768 - 256 = 512
512 ÷ 256 = 2
2 x 100 = 200%
Example