-0.3% is the change from 668 to 666
Calculation steps:
[( 666 - 668 ) ÷ 668] x 100 = -0.3%
Formula
Percentage change = [(666 - 668) / 668] x 100
Subtract the new number by the original number
666 - 668 = -2
-2 ÷ 668 = -0.0029940119760479044
-0.0029940119760479044 x 100 = -0.3%