Question

Explain why 7x 11 x 13+13 is a composite number.​

Answer 1

Composite numbers are 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.

So here.. the given number has 4 factors..
They are 7, 11, 13 and 2. { 2 is included because, two times 13 is added to the given number.

So, this number is a composite number..

Hope, it helps you.