Write all possible 2-digit numbers using the digits 4, 0 and 9. Repetition of digits is not allowed. Also find their sum.

We are required to write 2-digit numbers using the digits 4, 0 and 9, where repetition of digits is not allowed.

The digit 0 cannot be put at ten's place because that would make the number only 1-digit.

Keeping 4 at ten's place, 2-digit numbers are 40 and 49.

Keeping 9 at ten's place, 2-digit numbers are 90 and 94.

All possible 2-digit numbers: 40, 49, 90, 94.

Sum = 40 + 49 + 90 + 94

= 273

Hence, all possible 2-digit numbers are 40, 49, 90 and 94, and their sum is 273.