how to type in mathematical symbols?

Search Google. That’s not a WordPress issue.

If you’re already familiar with LaTeX, you can try implementing LaTeX in your WordPress installation. Alternatively, you can use an external engine to create images for your mathematical formulas. More information on both these ideas here:

https://sixthform.info/steve/wordpress/

https://www.forkosh.com/mimetex.html

Use the MS Word Equation editor, take screenies, add the notes as images?

Tks for the suggestions. I’m happily using LaTeX now

I recently created a new plugin for display of math equations within www.ads-software.com blogs. Readers of this forum thread may be interested in the plugin’s landing page:
https://www.ads-software.com/extend/plugins/wpmathpub/

Best regards,

Ron