Trying to make Sd

Hello im just trying to make a Game in this case sudoku, im made a basic 8x8 grid for sudoku whit 4 numbers but how can i click the blank button and click one of the 4 button whit nubers below to show on the blank button

Do you need to click the blank button first?

The reason I ask is because if you could have it the other way(click number button first)
You could store the number to a global variable and set the blank button's text to the global variable when it's clicked.

I think the other way will be harder to do.

Please see the few pages at this link …

That doc is for another puzzle type where you fill in numbers on a board from a custom popup keyboard.