100% is the change from 321 to 642
Calculation steps:
[( 642 - 321 ) ÷ 321] x 100 = 100%
Formula
Percentage change = [(642 - 321) / 321] x 100
Subtract the new number by the original number
642 - 321 = 321
321 ÷ 321 = 1
1 x 100 = 100%
Example