How to write a fraction in Microsoft Excel?

Solution 1:

• In Excel go to Insert → Object.
• From the list select "Microsoft Equation 3.0".
• Select the equation that suits your needs. In this case:

• Type 2, press TAB key to move the cursor and then 3.

This is my result:

Solution 2:

Inside of a text box (Insert→Text Box), but not inside of a cell unfortunately, you can use Alt+= (or "New Equation" on the insert tab). This lets you freely type an equation (or use the ribbon's editor); typing x/y will automatically reformat it to a fraction, or you can manually insert a fraction and type into it.

I recommend this over Insert→Object because this type of equation uses a newer, cleaner editor (and you don't need to wait for the objects list to load). Neither option can be used within a cell, so this one is preferable.