19.53% is the change from 645 to 771
Calculation steps:
[( 771 - 645 ) ÷ 645] x 100 = 19.53%
Formula
Percentage change = [(771 - 645) / 645] x 100
Subtract the new number by the original number
771 - 645 = 126
126 ÷ 645 = 0.19534883720930232
0.19534883720930232 x 100 = 19.53%