Sorry i'm quite new to permutation and combination, as i'm actually home studied and i kinda lost somewhere~
Let A={1,2,3,4,5,6}
Permutation of set A end with 6 should be (6-1)! = 5!
The question asked to find how many permutation of set A contains the substring 23? = can i calculate that (6-2)! ?
Then the next question asked to fin how many permutation of set A contains the substring 23 "together in any order?" <-- this part i don't quite understand.