-0.39% is the change from 257 to 256
Calculation steps:
[( 256 - 257 ) ÷ 257] x 100 = -0.39%
Formula
Percentage change = [(256 - 257) / 257] x 100
Subtract the new number by the original number
256 - 257 = -1
-1 ÷ 257 = -0.0038910505836575876
-0.0038910505836575876 x 100 = -0.39%