8400% is the change from 3 to 255
Calculation steps:
[( 255 - 3 ) ÷ 3] x 100 = 8400%
Formula
Percentage change = [(255 - 3) / 3] x 100
Subtract the new number by the original number
255 - 3 = 252
252 ÷ 3 = 84
84 x 100 = 8400%
Example