309.09% is the change from 99 to 405
Calculation steps:
[( 405 - 99 ) ÷ 99] x 100 = 309.09%
Formula
Percentage change = [(405 - 99) / 99] x 100
Subtract the new number by the original number
405 - 99 = 306
306 ÷ 99 = 3.090909090909091
3.090909090909091 x 100 = 309.09%