Use data from 2 out of 3 Textbox

I am making 3 three Textbox named A,B and C. I will give user the option to put data in any of the two and depending on what 2 value are entered, do some calculations i.e. if data in inputted in A and B then calculation will be A+B or data is in B and C then B x C and so on. Unable to come up with any logic. I also want if 2 values are entered then the third one, no matter which is automatically blocked so that data cant be entered in all three at once.
Please provide any hint. I am literally scratching my head over this issue :sweat_smile:

trh this extension… If user pressed enter after inout in textbox, use the logic

I am already using this extension, but for other purposes. The thing is I am not using a built in Keyboard, rather some customized set of buttons. So enter button wont be possible I think. Thanks for help though. I was thinking something with built in blocks.

if you are using custom keyboard, show us what you ahve tried so that we can assist you further

Its not a full fledged keyboard, only 6 buttons arranged in a table layout (Number 1 to 6).

Why not use the normal textbox and set it as numeric only?

Seems promising. Checking right now. Will update.