340% is the change from 15 to 66
Calculation steps:
[( 66 - 15 ) ÷ 15] x 100 = 340%
Formula
Percentage change = [(66 - 15) / 15] x 100
Subtract the new number by the original number
66 - 15 = 51
51 ÷ 15 = 3.4
3.4 x 100 = 340%
Example