99% is the change from 502 to 999
Calculation steps:
[( 999 - 502 ) ÷ 502] x 100 = 99%
Formula
Percentage change = [(999 - 502) / 502] x 100
Subtract the new number by the original number
999 - 502 = 497
497 ÷ 502 = 0.9900398406374502
0.9900398406374502 x 100 = 99%