Let Q(n) denotes the number of seven digit numbers divisible by 9 which can be formed by using 7 distinct digits out of 1,2,3,4,5,6,7,8,9. Then which of the following is/are not the value of Q(n)

Explanation

Sum of the given `9` digits ` = 1+2+3+4+5+6+7+8+9 = 45`

Now, we have to select `7` digits.

The number will be divisible by `9` if sum of those `7` digits is divisible by `9`.

Minimum sum of two digits that we do not select `= 1+2 = 3`

Maximum sum of two digits that we do not select `= 8+9 = 17`

So, the sum of the `7` digits will lie between `45-17` and `45-3`, that is sum will be between `28` and `42`.

Now, there is only number `36` that is divisible by `9`.

So, the seven digits will have sum `36` in order to the number to be divisible by `9`.

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