21.6% is the change from 639 to 777
Calculation steps:
[( 777 - 639 ) ÷ 639] x 100 = 21.6%
Formula
Percentage change = [(777 - 639) / 639] x 100
Subtract the new number by the original number
777 - 639 = 138
138 ÷ 639 = 0.215962441314554
0.215962441314554 x 100 = 21.6%