1.

The total number of 9-digit number which have all different digits isA. `10"!"`B. `9"!"`C. `9 xx 9"!"`D. `10 xx 10"!"`

Answer» Correct Answer - C
We have to form 9-digit number with the digit 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 cannot be placed at the first place from left. So, first place from left can be filled in 9 ways.
Since, repetition is not allowed, so remaining 8 places can be filled in `9"!"` ways.
`therefore` Required number of ways `=9 xx 9"!"`


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