239.61% is the change from 255 to 866
Calculation steps:
[( 866 - 255 ) ÷ 255] x 100 = 239.61%
Formula
Percentage change = [(866 - 255) / 255] x 100
Subtract the new number by the original number
866 - 255 = 611
611 ÷ 255 = 2.396078431372549
2.396078431372549 x 100 = 239.61%