VS 2019 How to get data in a textbox when clicked on a particular button?

Hi,

I have some buttons (each button's caption has a number on it) and it is in a separate Groupbox on my form.

What I want now is, when I click on any button in a specific groupbox, it should take the first character of that groupbox and and "-" then the button caption text and show it in a TableNumber.Text textbox.

Example: If I click on 6 number button in a "Garden" groupbox then it should show "G-6" in TableNumber.Text textbox.

Thanks in advance.

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