Question

Show that $5\ast 7\ast 11\ast 13+55$ is a composite number.

Answer 1

Composite number: A whole number that can be divided exactly by numbers other than $1$ or it self.

$5\ast 7\ast 11\ast 13+55$

$\Rightarrow 5(1\ast 7\ast 11\ast 13+11)$

$\Rightarrow 5\ast 11(91+1)$

$\Rightarrow 5\ast 11\left(92\right)$

$\Rightarrow 5\ast 11(2^2\ast 23)$

$\Rightarrow 5\ast 11\ast 2\ast 2\ast 23$

So, given number is the composite number because it is the product of more than one prime numbers.