AoPS Wiki:Problem of the Day/September 1, 2011
In how many ways can the letters in the word "mathematical" be arranged if exactly one of the following criteria must be met:
1) The two a's are NOT next to each other.
2) The two m's are NOT next to each other.
3) No a is next to an m.
This Problem of the Day needs a solution. If you have a solution for it, please help us out by adding it.