How to write subscripts in Microsoft Office formulas

In Office’s built-in equation editor, you can type ^ (caret) for superscript followed by your text, and subscript is _ (underscore) followed by the text. 

You must enter a space after entering. For example, 

e_r SPACE next letter 

will give you 

er 

(Reprinted by https://superuser.com/questions/128240/how-to-write-subscripts-in-microsoft-office-formulas)