450% is the change from 18 to 99
Calculation steps:
[( 99 - 18 ) ÷ 18] x 100 = 450%
Formula
Percentage change = [(99 - 18) / 18] x 100
Subtract the new number by the original number
99 - 18 = 81
81 ÷ 18 = 4.5
4.5 x 100 = 450%
Example