Like the other features offered by Gemini in Google applications (documents, Gmail, etc.), the integration of Gemini in Google Sheets requires a paying and is not offered with the free version of Gemini.
There are two possibilities. The first is to have a Subscription Gemini Advanced. This formula allows anyone, including the general public, to take full advantage of Gemini by raising the limits of messages, using the last models, and therefore taking advantage of the integrations in Google Workspace.
For professional users, it is also possible to go through a subscription Google Standard or Superior Workspace Business.
If you have one of these two subscriptions, you should see a Gemini icon Next to your profile photo. This allows you to open the side panel allowing to interact with Gemini.
A first interaction that you may have with an existing table is to summarize it, which you can do from the document by clicking on the button “Summarize this table”but also from the Google Drive interface.
