-3.73% is the change from 671 to 646
Calculation steps:
[( 646 - 671 ) ÷ 671] x 100 = -3.73%
Formula
Percentage change = [(646 - 671) / 671] x 100
Subtract the new number by the original number
646 - 671 = -25
-25 ÷ 671 = -0.037257824143070044
-0.037257824143070044 x 100 = -3.73%