How many 8 digit mobile numbers can be formed if at least one digi | Filo
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Class 11

Math

Algebra

Permutations and Combinations

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How many digit mobile numbers can be formed if at least one digit is repeated?

Correct Answer: Option(d)
Solution:
At least one digit is repeated Total No. digit is repeated
For total permutations,
Any of the digit can be filled by any of the numbers.
Total times
For no digit to be repeated:
Let first digit be any of the numbers,
Next digit can be any of the remaining and so on.....
Required
Hence, the answer is
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