3.45% is the change from 812 to 840
Calculation steps:
[( 840 - 812 ) ÷ 812] x 100 = 3.45%
Formula
Percentage change = [(840 - 812) / 812] x 100
Subtract the new number by the original number
840 - 812 = 28
28 ÷ 812 = 0.034482758620689655
0.034482758620689655 x 100 = 3.45%