Using if else in textbox

Would it be possible if for example your setup is like this


I want my app to be like a legit calculator, would it be possible if for example textbox_p or 1 is selected, then except of typing the data you would just need to click or tap the button then it would only appear on that selected textbox.
if possible what would the code be.

Have you searched the Gallery for 'Calculator' ?

There must be loads of them there.