229.41% is the change from 255 to 840
Calculation steps:
[( 840 - 255 ) ÷ 255] x 100 = 229.41%
Formula
Percentage change = [(840 - 255) / 255] x 100
Subtract the new number by the original number
840 - 255 = 585
585 ÷ 255 = 2.2941176470588234
2.2941176470588234 x 100 = 229.41%