3.25% is the change from 646 to 667
Calculation steps:
[( 667 - 646 ) ÷ 646] x 100 = 3.25%
Formula
Percentage change = [(667 - 646) / 646] x 100
Subtract the new number by the original number
667 - 646 = 21
21 ÷ 646 = 0.032507739938080496
0.032507739938080496 x 100 = 3.25%