-13.67% is the change from 256 to 221
Calculation steps:
[( 221 - 256 ) ÷ 256] x 100 = -13.67%
Formula
Percentage change = [(221 - 256) / 256] x 100
Subtract the new number by the original number
221 - 256 = -35
-35 ÷ 256 = -0.13671875
-0.13671875 x 100 = -13.67%