-98.5% is the change from 665 to 10
Calculation steps:
[( 10 - 665 ) ÷ 665] x 100 = -98.5%
Formula
Percentage change = [(10 - 665) / 665] x 100
Subtract the new number by the original number
10 - 665 = -655
-655 ÷ 665 = -0.9849624060150376
-0.9849624060150376 x 100 = -98.5%