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," "#