24.9% is the change from 257 to 321
Calculation steps:
[( 321 - 257 ) ÷ 257] x 100 = 24.9%
Formula
Percentage change = [(321 - 257) / 257] x 100
Subtract the new number by the original number
321 - 257 = 64
64 ÷ 257 = 0.2490272373540856
0.2490272373540856 x 100 = 24.9%