-97.5% is the change from 680 to 17
Calculation steps:
[( 17 - 680 ) ÷ 680] x 100 = -97.5%
Formula
Percentage change = [(17 - 680) / 680] x 100
Subtract the new number by the original number
17 - 680 = -663
-663 ÷ 680 = -0.975
-0.975 x 100 = -97.5%
Example