-1.35% is the change from 669 to 660
Calculation steps:
[( 660 - 669 ) ÷ 669] x 100 = -1.35%
Formula
Percentage change = [(660 - 669) / 669] x 100
Subtract the new number by the original number
660 - 669 = -9
-9 ÷ 669 = -0.013452914798206279
-0.013452914798206279 x 100 = -1.35%