180% is the change from 15 to 42
Calculation steps:
[( 42 - 15 ) ÷ 15] x 100 = 180%
Formula
Percentage change = [(42 - 15) / 15] x 100
Subtract the new number by the original number
42 - 15 = 27
27 ÷ 15 = 1.8
1.8 x 100 = 180%
Example