672.5% is the change from 40 to 309
Calculation steps:
[( 309 - 40 ) ÷ 40] x 100 = 672.5%
Formula
Percentage change = [(309 - 40) / 40] x 100
Subtract the new number by the original number
309 - 40 = 269
269 ÷ 40 = 6.725
6.725 x 100 = 672.5%
Example