Using 1/2 symbol

You cannot directly enter fractions (or other glyphs) from the iPad on-screen keyboard. There are keyboard Apps that add additional keyboards that you can install from the App Store - or you can use the native text-replacement feature of iOS/iPadOS.

This external link describes how you can set-up text replacement to enter fractions:

https://medium.com/@dannymcclain/replace-typed-fractions-with-real-fractions-on-ios-and-mac-404df2c7d90b