-90% is the change from 680 to 68
Calculation steps:
[( 68 - 680 ) ÷ 680] x 100 = -90%
Formula
Percentage change = [(68 - 680) / 680] x 100
Subtract the new number by the original number
68 - 680 = -612
-612 ÷ 680 = -0.9
-0.9 x 100 = -90%
Example