Prime numbers are those that cannot be divided by another number (other than themselves and 1). In other words, prime numbers have factors of themselves and 1.
For example, 3 is a prime number because its only factors are 3 and 1.
6 is not a prime number because it can be factored to 3*2.
3*2 * 1 = 24 ways . It is called arrangement or permutations, while if you need to group some objects it is called combination and there we need to consider unique groups only.
