Question

If an employee ID code must consist of 3 non-repeating digits and each digit in the code must be a prime number, how many ID codes can be created?

Answer 1

24

Explanation:

The given scenario is a permutation problem. The number of ID codes could be created using permutation because there is no repetition and so order is important. There are four prime numbers that are {2,3,5,7}. So, number of ID codes could be created is calculated using nPr.

Here n=total prime numbers=4

r=chosen number=3.

So,nP4=4P3=4!/(4-3)!=4!=24. Hence there are 24 ID codes that could be generated.