Question

Which of the following natural numbers are composite?

• A. $233$
• B. $788$
• C. $169$
• D. $121$

Answer 1

Answer: (B), (C), (D)

$121$

All the natural numbers having factors other than $1$ and itself the number are composite numbers.
Also, all the even numbers except $2$ are composite because they always have $2$ as their factor. $2$ is the only even prime number.

$788$ is even. Hence, it is a composite number.

$169=13\times 13$, $13$ is factor of $169$. Hence, it is a composite number.

similarly, $121$ is divisible by $11$. Hence, $121$ is a composite number.

$233$ do not have factor other than 1 and itself. Hence it is a prime number not composite number.