Question

How many different three-letter initials with none of the letters repeated can people have?

Answer 1

This is a probablity question

there are 3 slots, 26 letters of the alphabet

so in the first slot, we have 26 possible letters
2nd slot, we have 25 possible letters (we used one for the first slot)
3rd slot, we have 24 possible letters, (we used 2 for first and 2nd slot)

so in total, we have 26*25*24 or 15600 different 3 letter initials with no repeated letters