Format fractions automatically in Keynote on Mac
You can set Keynote to automatically format fractions as you type them. The setting doesn’t apply to fractions you type in table cells or comments.
Choose Keynote > Preferences (from the Keynote menu at the top of your screen).
Click Auto-Correction at the top of the preferences window.
In the Formatting section, select the “Automatically format fractions” checkbox.
The setting applies to text you type from now on—it doesn’t change fractions you’ve already typed.