We are going to name the people A, B, C, and D
1. A, B, C, then D
2. A, B, D, then C
3. A, C, B then D
4. A, C, D, then B
5. A, D, B, then C
6. A, D, C, then B
So at this rate, if there is 6 for the first letter, then there will be 6 for the others, so 6 x 4 = 24, so there are 24 different outcomes.
Hope this helped!