-2.78% is the change from 648 to 630
Calculation steps:
[( 630 - 648 ) ÷ 648] x 100 = -2.78%
Formula
Percentage change = [(630 - 648) / 648] x 100
Subtract the new number by the original number
630 - 648 = -18
-18 ÷ 648 = -0.027777777777777776
-0.027777777777777776 x 100 = -2.78%