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प्रश्न
How many words, with or without meaning can be formed from the letters of the word 'MONDAY', assuming that no letter is repeated, if (i) 4 letters are used at a time
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उत्तर
There are six letters in the word MONDAY.
4 letters are used at a time:
Four letters can be chosen out of six letters in 6C4 ways.
So, there are 6C4 groups containing four letters that can be arranged in \[4!\]ways.
∴ Number of ways = \[{}^6 C_4 \times 4! = \frac{6!}{4! 2!} \times 4! = \frac{6!}{2!} = 360\]
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