Math CentralQuandaries & Queries


Question from Shelbie:

How many 3 letter combinations are possible, if you can repeat each letter?
I learned an easy way to do this in school, but fail to remember what that was...

Hi Shelbie,

You have 26 choices for the first letter and regardless of what letter you choose you have 26 choices for the second letter. Hence there are 26 × 26 possible two letter words. You can extend each of these possible two letter words into a three letter word by adding one of 26 possible letters and hence there are 26 × 26 × 26 possible three letter words.


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