665% is the change from 40 to 306
Calculation steps:
[( 306 - 40 ) ÷ 40] x 100 = 665%
Formula
Percentage change = [(306 - 40) / 40] x 100
Subtract the new number by the original number
306 - 40 = 266
266 ÷ 40 = 6.65
6.65 x 100 = 665%
Example