Aptitude - Odd Man Out and Series - Discussion

Somebody please explain me clearly what is a composite number.

If any number has more then two factors(1 and that number itself) then that number is called composite number.

Example:

9 has 1,3,9 as factor ,so its composite number.

11 has 1,11 as the factor so it is not composite number since it is divisible by 1 and by that number itself.

11 is a prime number so it became odd member of the series.
Any number which is divisible by 1 and itself is a prime number, and any number which is not prime is called a composite number.
But one does not belong to both these categories i.e., prime or composite.

Yes.
A composite number is a positive integer which has a positive divisor other than one or itself. In other words a composite number is any positive integer greater than one that is not a prime number.

akhil answer is correct.

COMPOSITE NUMBERS MEANS : NUMBERS WHICH ARE DIVIDED BY ITSELF AND ONE AND ALSO OTHER THAN ONE OR ITSELF. For e.g 9 is divided by one, it gets divided by itself (i.e 9) and also other numbers is 3. So 9 is comp.

Whereas 11 is divided by one and 11 itself but there is no other numbers except one and itself, so its not comp. OK, guys I hope you understand this :).

All numbers except prime numbers are known as composite numbers. Here 11 is a prime number so it is different.

Number which are not prime is called composite numbers. 11 is prime number. Rest are composite numbers.

I think 4 is divisible by 2.

6/3.
8/2.
9/3.
10/2.

11 is not divisible by 3.
12/2.

So 11 is odd man.

This is a flawed question. They should update it.

They use the word 'composite' to mean non-prime. Every number is either prime (divisible only by itself and one) or non-prime (having factors other than itself and one).

The question uses a sequence of natural numbers: 7 4 6 8 9 10 11 12.

They describe every number except 11 as 'composite' (having other factors apart from itself and one) but 7 is also in that category. So they made a mistake. End of story.