309.09% is the change from 66 to 270
Calculation steps:
[( 270 - 66 ) ÷ 66] x 100 = 309.09%
Formula
Percentage change = [(270 - 66) / 66] x 100
Subtract the new number by the original number
270 - 66 = 204
204 ÷ 66 = 3.090909090909091
3.090909090909091 x 100 = 309.09%