# How do you write all possible selections of two letters that can be formed from the letters A, B, C, D, E, and F?

##### 1 Answer

Nov 19, 2017

#### Answer:

You fix one of the letters to be the first and then write out all possible second letters, assuming replacement is allowed. Do this for every letter.

#### Explanation:

For example, fix A to be the first letter. Then all the possible two letter words are AA, AB, AC, AD, AE and AF. And then do this for every letter.

A way to check we've written out all possibilities is to find the total no. of possibilities and check if we've met that.

We have