What numbers between `11` and`19` are composite numbers?

Compossite numbers are those numbers who have factors other than `1` and themselves.

As even numbers are multiples of `2`, between `11` andd `19`

we have `12,14,16,18` as composite numbers

among odd numbers `13,15,17`

only `15` has factors other than `1` and itself.

Hence, between `11` and `19` we have `12,14,15,16,18` as composite numbers.

Composite Numbers are those numbers which have factors other than one and itself.

Example : 4 is a composite number as it has factors 1, 2 and 4.
(In fact it is the smallest composite number.)

Between `11 and 19`, there are `7` numbers:

`12, 13, 14, 15, 16, 17, 18`

Here `11` is not composite, instead it is prime (those numbers which have only `1` and themselves as factors)
[`11` has only two factors, `1 and 11`.]

`12` is composite; as `12` has factors `1, 2, 3, 4, 6 and 12.`

`13` is again prime, having only `1 and 13` itself as factors.

`14 " has " 1, 2, 7 and 14`
`15 " has " 1, 3, 5 and 15`
`16 " has " 1, 2, 4, 8 and 16`
These are all composite numbers.

`17` is prime

`18` is composite.

Hence explained my answer.

The numbers 'between' `11 and 19` are:

`12," "13," "14," "15," "16," "17," "18," "`

All numbers (except 1) are either prime or composite.

Prime numbers have exactly `2` factors while
Composite numbers have more than `2` factors.

There are more composite numbers than prime numbers, so the quickest way to find the composite numbers in a given set, is to simply exclude the primes.

The prime numbers between `11 and 19` are:

`color(blue)(13 and 17)`, so all the rest are composite.

`12," "cancelcolor(blue)(13)," "14," "15," "16," "cancelcolor(blue)(17)," "18," "`