-99.1% is the change from 665 to 6
Calculation steps:
[( 6 - 665 ) ÷ 665] x 100 = -99.1%
Formula
Percentage change = [(6 - 665) / 665] x 100
Subtract the new number by the original number
6 - 665 = -659
-659 ÷ 665 = -0.9909774436090225
-0.9909774436090225 x 100 = -99.1%