The number of six-digit numbers all digits of which are odd, is …… .

Options

A. `(5)/(2)xx6!`
B. 6!
C. `(1)/(2)xx6!`
D. none of these

Explanation

There are five odd digtis. Therefore, in a 6 digit number of odd digits one of the odd digits will repeat. One odd digit can be chosen in `""^(5)C_(1)` ways. Now, we have 6 digits which can be arranged in `(6!)/(2!)` ways.
`:.` Required number of numbers `=""^(5)C_(1)xx(6!)/(2!)xx6!`