You have four tiles that say M, A, T, and H. How many words can you form from these tiles? For example, you can form "AMH" and "TH". (The words do not have to be valid English words.)
Case 1: 1 letter word
There are 4 ways to do this.
Case 2: 2 letter word
There are \(4\cdot3\) , ways to do this.
Case 3: 3 letter word
There are \(4\cdot3\cdot2=24\), ways to do this.
Case 4: 4 letter word
There are \(4!=24\), ways to do this.
Add them all up, 4 + 12 + 24 + 24 = 64
That will be your final answer,
I hope this helped,
Gavin