31.01% is the change from 645 to 845
Calculation steps:
[( 845 - 645 ) ÷ 645] x 100 = 31.01%
Formula
Percentage change = [(845 - 645) / 645] x 100
Subtract the new number by the original number
845 - 645 = 200
200 ÷ 645 = 0.31007751937984496
0.31007751937984496 x 100 = 31.01%