zero+nine=nine, zero+nintynine=nintynine, zero+ninehundred and nintynine=nine hundred and nintynine, zero+nine thousand nine hundred ninty nine, zero+nine lakhs nine thousand nine hundred ninty nine
If you actually mean "combination" (order does not matter) and you want 10 digits each used exactly once, then the answer is 1. Look at formulas for permutations and combinations.