You'll need an android tablet with google play.
Install scorchcad.

Very quickly you'll release that constantly switching between keyboards for numbers and brackets is a real pain in the posterior.
Then you'll realise that going back to earlier lines with the tap and hope method is also a pita.

So what you do is go back to google play and install hackers keyboard, the one with the big 'esc' key symbol.

And viola !
You can now use a standard pc keyboard layout, complete with all symbols, numbers and brackets needed for openscad scripts. You even have the arrow keys for easily moving around the script.
No swapping ever necessary :-)

Openscad on a tablet now just as easy as on a pc or add on hardware keyboard.