Count words in slides and notes pages
To https://wordcounter.tools in both your PowerPoint presentation's slides and your notes page, do the following:
On the File tab, click Info.
At the bottom of the rightmost pane, click Show All Properties. The word property counts all text on slides and notes pages.
Count indicates the words in the notes page
You can also count words in a PowerPoint presentation's notes page, but it's best to do so in Word.
On the File tab, click Export > Create Handout.
In the Send to Microsoft Word dialog box, click the page layout that you want, and then do one of the following:
To paste the content that you want to keep unchanged when updating the content in the original PowerPoint presentation, click Paste, and then click OK.
To make sure that any updates that occur to the original PowerPoint presentation are reflected in the Word document, click Paste the link, and then click OK.
The presentation opens as a Word document in a new window. You can edit, print, or save as you would with any Word document. Word automatically counts the number of pages and words in your document and displays them in the status bar at the bottom of the workspace.
If you don't see word count in the status bar, right-click the status bar, and then click word count.
Danial Micheal commented
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Google Sheets and Google Slides don't offer a word count feature https://www.myatriumhealth.biz/