100.2% is the change from 499 to 999
Calculation steps:
[( 999 - 499 ) ÷ 499] x 100 = 100.2%
Formula
Percentage change = [(999 - 499) / 499] x 100
Subtract the new number by the original number
999 - 499 = 500
500 ÷ 499 = 1.002004008016032
1.002004008016032 x 100 = 100.2%