Hello flbeachman,
Thank you for posting to community forum.
According to description you want to add the dynamic calculation to a table and get a sum of the data in cells.
As you have noticed we can’t do the dynamic calculation in tables with Equation feature in OneNote and I’m afraid OneNote doesn’t have a feature to use Formula for tables as it is in Excel or Word.
We understand the inconvenience and apologize for it, to address your concern we suggest you leave feedback, so the developer team pay attention to this and add this feature in future updates. We have found a similar request in Microsoft Feedback Portal Dynamic tables you can sort and put simple formulas · Community (microsoft.com)
You may add third party add-in to OneNote if you want to use the calculations in tables.
As another option you can insert Excel spreadsheet to your page with Insert > Spreadsheet.
If you want to know what version of OneNote you use click on File > Account.
Best Regards,
Igor