-3.14% is the change from 668 to 647
Calculation steps:
[( 647 - 668 ) ÷ 668] x 100 = -3.14%
Formula
Percentage change = [(647 - 668) / 668] x 100
Subtract the new number by the original number
647 - 668 = -21
-21 ÷ 668 = -0.03143712574850299
-0.03143712574850299 x 100 = -3.14%