Just frame the text and click on the superscript.

I will demonstrate the detailed steps below:

(Computer model: MacBook Air, software version: Word 2021)

1. Open Word and frame the number that needs to be marked;

2. Click the superscript above;

3. The operation of adding a number to the upper right corner in word is completed!

The above is a tutorial on adding numbers in the upper right corner of Word. I hope it will be helpful to you~