100.31% is the change from 319 to 639
Calculation steps:
[( 639 - 319 ) ÷ 319] x 100 = 100.31%
Formula
Percentage change = [(639 - 319) / 319] x 100
Subtract the new number by the original number
639 - 319 = 320
320 ÷ 319 = 1.0031347962382444
1.0031347962382444 x 100 = 100.31%