Question

Explain why $3\times 5\times 7+7$ is a composite number.

Answer 1

$3\times 5\times 7+7=105+7=112$. $112$ is an even number and is therefore a composite number. Also, $112$ is divisible by other numbers such as $2,4,7,8,14,16,28$ and $56$ apart from itself $112$ and $1$

Hence $3\times 5\times 7+7$ is a composite number