Units of Measure
If you're working within the context of a number question, you have the option to setup various Units of Measure, which allow you to correlate the given number value to a strongly tied unit.
To edit the units of measure for a question, simply click the button labeled " Edit Units of Measure" displayed in the image below:
And use the subsequent dialog to Add or Edit your Units of Measure:
Make sure to click I'm Done to make sure your changes are saved! And that's it! The question will now display a corresponding dropdown picker for units of measure when answering this question on the form.