21.5% is the change from 642 to 780
Calculation steps:
[( 780 - 642 ) ÷ 642] x 100 = 21.5%
Formula
Percentage change = [(780 - 642) / 642] x 100
Subtract the new number by the original number
780 - 642 = 138
138 ÷ 642 = 0.21495327102803738
0.21495327102803738 x 100 = 21.5%