-3.29% is the change from 638 to 617
Calculation steps:
[( 617 - 638 ) ÷ 638] x 100 = -3.29%
Formula
Percentage change = [(617 - 638) / 638] x 100
Subtract the new number by the original number
617 - 638 = -21
-21 ÷ 638 = -0.032915360501567396
-0.032915360501567396 x 100 = -3.29%