To make n entry code, you need to first choose a single-digit number and then two letters, which can repeat.

Would you use permutation or combination?

How many entry codes can you make?

Question

To make n entry code, you need to first choose a single-digit number and then two letters, which can repeat.

Would you use permutation or combination?

How many entry codes can you make?

turingtest · Answer

if you had to choose the two letters first, would it make a difference? does it matter which letter you choose first?
if so, then permutation, otherwise combination

btaylor · Answer

It is a combination, since you aren't limited by choosing in order. You could choose the second letter first, and it wouldn't affect  the first one at all.
There are 10 digits (0-9) and 26 letters, so you have
10 x 26 x 26 choices =  6760 choices

highschoolmom2010 · Answer

is that all i had to do?