How many 3-letter "words" can be formed from the standard 26-letter alphabet, if the first letter must be a vowel (A, E, I, O, or U)? (We aren't necessarily talking about English words; something like EQX is perfectly valid here.)
Since each "word" must start with a vowel, there are 5 choices for the first letter.
Each of the following 2 letters can be any of the 26 letters of the alphabet.
Multiplying the choices together, we get 5 x 26 x 26 or 3380 possibilities.