99.6% is the change from 250 to 499
Calculation steps:
[( 499 - 250 ) ÷ 250] x 100 = 99.6%
Formula
Percentage change = [(499 - 250) / 250] x 100
Subtract the new number by the original number
499 - 250 = 249
249 ÷ 250 = 0.996
0.996 x 100 = 99.6%
Example