As the title said, I have an assignment where we are asked: How many 2-digit numbers can be formed from even-numbered digits if the repetition of the digit is not allowed?
I've tried answering it myself but I am not sure if it's correct. What I did was multiply 4 by 3, since there are 4 even-numbered digits (2, 4, 6, 8). And since repetition is not allowed, for the ones digit, I did 4 since nothing has been used yet and for the tens digit I only used 3 since one digit has been used before. Please correct me if I'm wrong.
Sorry if my explanation is bad, I have a hard time trying to explain things and this is my first time posting. Many thanks!
Edit: Okay, just a quick update. I asked my teacher and apparently, both 12 and 16 are considered answers. Case closed! 🙂
Best Answer
What about the number $0$? While it can't be placed at the first digit, it can be placed at the second digit.
The first place has $4$ choices, after picking the first place, we have $4$ choices for the second place.
$4 \times 4 = 16$.