Answer:
Total derangement = 4
Step-by-step explanation:
To find - How many derangement of {1, 2, 3, 4, 5, 6} begin with the integers 1, 2, and 3, in some order?
Solution -
Given that,
The first three numbers are 1, 2, 3
The only derangement possible are - 231 and 312
Now,
The remaining elements 4, 5, 6 are the 4th, 5th and 6th number in the derangement
Now,
In order for the permutation of the derangement, the only possibility for 123 are 564 and 645
∴ we get
The Total derangement are -
231564
231645
312564
312645
So,
Total derangement = 4
