34.24% is the change from 257 to 345
Calculation steps:
[( 345 - 257 ) ÷ 257] x 100 = 34.24%
Formula
Percentage change = [(345 - 257) / 257] x 100
Subtract the new number by the original number
345 - 257 = 88
88 ÷ 257 = 0.3424124513618677
0.3424124513618677 x 100 = 34.24%