Question

Why is $99$ a composite number?

Answer 1

Hint: Composite numbers are those numbers that are divisible by a number other than $1$ and the number itself that means the number which has more than two factors is called composite number. For example: $4,6$ are composite numbers as they are also divisible by 2 and 3 respectively.

Complete step by step solution:
To check whether $99$ is a composite number we need to check the divisibility of $99$ by different numbers.
If $99$ is divisible by any other number other than $1$ and $99$ itself then it is a composite number otherwise not.
Let’s check the divisibility of $99$.
$99 \div 1 = 99$
$99$ is divisible by $1$ . So, $1$ is a factor of $99$.
$99 \div 3 = 33$
$99$ is divisible by $3$. So, $3$ is a factor of $99$.
$99 \div 9 = 11$
$99$ is divisible by $9$. So, $9$ is a factor of $99$.
$99 \div 11 = 9$
$99$ is divisible by $11$.So, $11$ is a factor of $99$.
$99 \div 33 = 3$
$99$ is divisible by $33$. So, $33$ is a factor of $99$.
$99 \div 99 = 1$
$99$ is divisible by $99$. So, $99$ is a factor of $99$.
From this, it can be concluded that $99$ is a composite number as it has more than two factors.
Composite numbers can also be defined as the integers that can be generated by multiplying the two smallest positive integers. We can write $99$ as the product of two smallest positive integers as $ \Rightarrow 3 \times 33 = 99$
$ \Rightarrow 11 \times 9 = 99$
Hence, we can conclude that $99$ is a composite number as it has more than two factors i.e.,$1,3,9,11,33,99$.

Note:
Composite numbers can be defined as the whole numbers that have more than two factors. Whole numbers that are not prime are composite numbers, because they are divisible by more than two numbers. Note that $0$ is neither a prime nor composite number since any number times zero equals zero, there are infinite numbers of factors for a product of zero and composite numbers can never have infinity numbers of factors.