How many different words can be formed with the letters of word 'SUNDAY'? How many of the words begin with N? How many begin with N and end in Y?
Total number of words that can be formed with the letters of the word SUNDAY = 6! = 720
Now, if we fix the first letter as N, the remaining 5 places can be filled with the remaining 5 letters in 5! ways, i.e. 120.
If we fix the first letter as N and the last word as Y:
Remaining 4 places can be filled with 4 letters in 4! ways = 24