1997.5% is the change from 40 to 839
Calculation steps:
[( 839 - 40 ) ÷ 40] x 100 = 1997.5%
Formula
Percentage change = [(839 - 40) / 40] x 100
Subtract the new number by the original number
839 - 40 = 799
799 ÷ 40 = 19.975
19.975 x 100 = 1997.5%
Example