Q. The number of letters words, with or without meaning which can be formed out of the letters of the word 'NUMBER'
Statement I : When repetition of letters is not allowed is
Statement II : When repetition of letters is allowed is .
Choose the correct option.

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Solution:

I. Number of 3 letter words (repetition not allowed)

(as first place can be filled in 6 different ways, second place can be filled in 5 different ways and third place can be filled in 4 different ways)
II. Number of 3 letter words (repetition is allowed)

(as each of the place can be filled in 6 different ways)