How many words can be formed from 5 different letters?
There are 26 letters in the English alphabet. Therefore, we have 26 options for the first letter.
Then, since the second letter must be different, we have 25 different options.
Similarly, for the third letter, we have 24 options, and so on.
Therefore, using the fundamental counting principle, the total number of words we can make from five different letters is .
We write this as .