290.23% is the change from 256 to 999
Calculation steps:
[( 999 - 256 ) ÷ 256] x 100 = 290.23%
Formula
Percentage change = [(999 - 256) / 256] x 100
Subtract the new number by the original number
999 - 256 = 743
743 ÷ 256 = 2.90234375
2.90234375 x 100 = 290.23%