Since I am not divisible by 2, I am an odd integer.
Odd integers all end with 1, 3, 5, 7, 9.
Since the sum of my 3 digits is only 4, my last digit can only be 1 or 3.
If my last digit were 3, then that would leave only 1 for my first two digits
to have as a sum. Then I could be only 103, but 103 is not a multiple of 7.
Therefore my last digit must be 1.
Since my first two digits must have sum 3, they can only be 12, 21 or 30.
So I can only be 121, 211, or 301. Of these only 301 is divisible by
7. So I am 301.
Edwin
