Which is the smallest nine digit odd number?
117
As the number is odd it must end in an odd digit; the odd digits are 1, 3, 5, 7, 9 and the smallest is 1 which is the sum of 1 and 0. Thus the smallest 7-digit number which meets your criteria is 1,001,001
101
What is the least possible 6 digit odd number with only using 1 to 9 once
It is the digit 9
9
987654321
-9
9
The smallest number that is both odd and composite is 9, which is divisible by 3. The odd numbers are 1, 3, 5, 7, 9, 11, ..., and 1, 3, 5, and 7 are all prime. It is 9 that is the smallest odd composite number.
9
10 is the smallest 2-digit whole number.