Question

What numbers between 11 and 19 are composite numbers?

Answer 1

Hint: Here in this question, we have to find or list out the composite number between 11 and 19. For this, first we must have prior knowledge about composite numbers and should know the factors of numbers between 11 and 19 then by the definition and its property of composite number we can approach the solution of the question.

Complete step by step answer:
A prime number (or a prime) is a natural number greater than 1 with only two factors – themselves and 1 and that is not a product of two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number.

Consider the given questions: We have to find the composite numbers between $11$ and $19$ to do. So, first we have to find the numbers present between them and the nature and factors of them. The natural numbers between $11$ and $19$ including ($11$ and $19$) are: $11$, $12$, $13$, $14$, $15$, $16$, $17$, $18$, $19$.
let’s differentiate the even numbers and odd numbers
Even numbers:$12$,$14$,$16$, $18$.
Odd numbers: $11$,$13$,$15$,$17$,$19$.

Since, we know that every even number except 2 has at least 1 factor except 1 and itself and not every odd number has factors more than 2.
$11$ has only two factors, $1$ and $11$ so it is not a composite number.
$12$ has two factors, $1$, $2$, $3$, $4$, $6$, $12$ so it is a composite number.
$13$ has two factors, $1$ and $13$ so it is not a composite number.
$14$ has two factors, $1$, $2$, $7$, $14$ so it is a composite number.
$15$ has two factors, $1$, $3$, $5$, $15$ so it is a composite number.
$16$ has two factors, $1$, $2$, $4$, $8$, $16$ so it is a composite number.
$17$ has only two factors, $1$ and $17$ so it is not a composite number.
$18$ has two factors, $1$, $2$, $3$, $6$, $9$, $18$ so it is a composite number.
$19$ has only two factors, $1$ and $19$ so it is not a composite number.

Hence, $12,\,\,14,\,\,15,\,\,16,\,$and $18$ are composite numbers.

Note: The concept of composite number which we used in the above solution can be explained as the number which is the multiple of 2 or more than 2 integers such that it has at least 1 divisor excluding number 1 and the number itself. These numbers which are the divisor of the number are named as the factors of the number . For example, composite numbers are even numbers except 2 and non-prime numbers.