CBSE Class 11-science Answered

Here we have to make 3 letter words.  That means we have to fill up three places by distinct letters of the English alphabets.

Since there are 26 letters of the English alphabet, the first place can be filled by anyone of these letters.  So, there are 26 ways of filling up the first place.  Now the second place can be filled up by anyone of the remaining 25 letters.  So, there are 25 ways of filling up the second place.  After filling up the first two places only 24 letters are left to fill up the third place.  So the third place can be filled in 24 ways.

Hence the required number of words = 26 x 25 x 24 = 15600