MCQ
The number of nine digit numbers that can be formed with different digits is:
  • A
    $9.8!$
  • B
    $8.9!$
  • $9.9!$
  • D
    $10!$

Answer

Correct option: C.
$9.9!$
The first digit is one of $(1, 2, 3, 4, 5, 6, 7, 8, 9) ($i.e., all expect $0).$
So, the no of ways $=9$
The remaining $8$ digits are to be taken from the remaining $9$ numbers.
So, the no of ways $= \ ^9\text{P}_8$
So, total no. of ways $=9\times\ ^9\text{P}_8$
$=9\times9!$

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