-99.1% is the change from 668 to 6
Calculation steps:
[( 6 - 668 ) ÷ 668] x 100 = -99.1%
Formula
Percentage change = [(6 - 668) / 668] x 100
Subtract the new number by the original number
6 - 668 = -662
-662 ÷ 668 = -0.9910179640718563
-0.9910179640718563 x 100 = -99.1%