Decimal & Fraction
The "Decimal/Fraction" select box under the "LRA/Part Settings" button is used to format the resulting "lengths" or "locations" and the part's "cut length".
If you use a tape measure that has fractions you may want to set these values to match up. With all NC or CNC machinery you will want to set the tolerance to 2 or 3 decimal places.
Make sure to change values in the Options menu which can be accessed by clicking the "Tools" menu and selecting "Options". The Decimal/Fraction adjustment menu can be found in the "General" tab, in the Tolerance section under "Lengths".