90% is the change from 420 to 798
Calculation steps:
[( 798 - 420 ) ÷ 420] x 100 = 90%
Formula
Percentage change = [(798 - 420) / 420] x 100
Subtract the new number by the original number
798 - 420 = 378
378 ÷ 420 = 0.9
0.9 x 100 = 90%
Example