Imagine that 12 people are deciding who is the first in queue. Each of them can be first, then you have 12 ways to choose somebody to be the first. Then remains 11 people and you have 11 ways to select who will be the second in queue. Then from 10 people you can choose in 10 ways who will be the third in queue, from 9 you have 9 ways to choose who will be the 4th and so on.
Using the product rule, you obtain that you have
[tex]12\cdot 11\cdot 10\cdot 9\cdot 8\cdot 7\cdot 6\cdot 5\cdot 4\cdot 3\cdot 2\cdot 1=12![/tex]
possible ways line up in a row 12 people for concert tickets. So, this situation involves permutations.
Answer: 12!
