CrossRoads:
Well, just take the inputs & do some math on it:
before reading clear the prior entries
digit1 = 0
digit0 = 0

after you get the entries
total = 10*(digit1) + digit0

Or, you will have a 4x3 keypad?
Make one of the keys = 10.
1-2-3-4-5-6-7-8-9-10-enter-clear
0 = 10,

= clear,

• = enter

Thanks, yes, 3x4,
I see now. I could do either of these...