As stated in the title above: How many 4-digit odd numbers can be formed using the digits 0, 1, 2 and 3 only if the repetition of the digit is not allowed?
I already have the answer for this and it is 8.
(2)(2)(1)(2) = 8
However, I do not understand how it became like that. Any understandable explanation would be appreciated!
Best Answer
Hint #1: Since the number is odd, then the unit's digit could only be either $1$ or $3$.
Hint #2: Since the number has $4$ digits, the thousand's digit cannot be $0$.
Can you finish?