Question

The number of all 6-digit numbers, which have all the digits distinct, is

• A. 9⁶
• B. C(9, 6)
• C. 9 x $9P_{5}$
• D. None of these

Answer 1

Answer: (C)

9 x $9P_{5}$

Answer 2

Extreme left place can be filled in 9 ways as any one of the 9 non-zero digits can be placed there. Corresponding to each way of doing so, the remaining five places can be filled in with remaining nine digits in $9P_{5}$ ways.

Hence, the required number of numbers

= 9 x $9P_{5}$