81.9% is the change from 420 to 764
Calculation steps:
[( 764 - 420 ) ÷ 420] x 100 = 81.9%
Formula
Percentage change = [(764 - 420) / 420] x 100
Subtract the new number by the original number
764 - 420 = 344
344 ÷ 420 = 0.819047619047619
0.819047619047619 x 100 = 81.9%