How many words, with or without meaning can be made from the letters of the word MONDAY, assuming that no letter is repeated, if
(i) 4 letters are used at a time
(ii) all letters are used at a time
(iii) all letters are used but first letter is a vowel.

The number of words can be formed =

=

= 360 words.

(ii) All letters are used at a time:

The number of words that can be formed = 6! = 720 words.

(iii) All letters are used but first letter is a vowel

The first letter of the word will have the letters O or A i.e. 2 ways.

The remaining places will be 5! Ways.

Therefore total number of words = 5! X 2 = 240 ways.