102.38% is the change from 420 to 850
Calculation steps:
[( 850 - 420 ) ÷ 420] x 100 = 102.38%
Formula
Percentage change = [(850 - 420) / 420] x 100
Subtract the new number by the original number
850 - 420 = 430
430 ÷ 420 = 1.0238095238095237
1.0238095238095237 x 100 = 102.38%