212.12% is the change from 99 to 309
Calculation steps:
[( 309 - 99 ) ÷ 99] x 100 = 212.12%
Formula
Percentage change = [(309 - 99) / 99] x 100
Subtract the new number by the original number
309 - 99 = 210
210 ÷ 99 = 2.121212121212121
2.121212121212121 x 100 = 212.12%