Certainly. What's in the cell right now? Meters, kilometers, millimeters,
micrometers? What's wrong with simply specifying whatever numeric format you
want?
In the number format section you can create a custom format like this
0.0 "mm" and apply it to the desired cells
This will display the entered or calculated number to 1 decimal place with
the mm tag at the end (13.1 mm). It does not do any conversion or
calculations, just shows the units. You can use as many decimal places as
you desire.