400% is the change from 51 to 255
Calculation steps:
[( 255 - 51 ) ÷ 51] x 100 = 400%
Formula
Percentage change = [(255 - 51) / 51] x 100
Subtract the new number by the original number
255 - 51 = 204
204 ÷ 51 = 4
4 x 100 = 400%
Example