Joe wants to find all the four-letter words that begin and end with the same letter. How many combinations of letters satisfy this property?
Pick a letter, there are 26 choices, that letter is the first and last letter in the word.
We then have 2 slots left and can choose any letters to fill them. There are 262 ways of choosing them
So there are 26x262 = 263 =17576 words with this property
