100.4% is the change from 249 to 499
Calculation steps:
[( 499 - 249 ) ÷ 249] x 100 = 100.4%
Formula
Percentage change = [(499 - 249) / 249] x 100
Subtract the new number by the original number
499 - 249 = 250
250 ÷ 249 = 1.0040160642570282
1.0040160642570282 x 100 = 100.4%