-97.79% is the change from 680 to 15
Calculation steps:
[( 15 - 680 ) ÷ 680] x 100 = -97.79%
Formula
Percentage change = [(15 - 680) / 680] x 100
Subtract the new number by the original number
15 - 680 = -665
-665 ÷ 680 = -0.9779411764705882
-0.9779411764705882 x 100 = -97.79%