Question & Answer » Mathematics Questions » Explain why 7 × 11 × 13 + 13 and 7 × 6 × 5 × 4 × 3 × 2 × 1 + 5 are Composite Numbers?

Explain why 7 × 11 × 13 + 13 and 7 × 6 × 5 × 4 × 3 × 2 × 1 + 5 are Composite Numbers?

Explanation:

  • Composite numbers, also known as composites in Mathematics, are numbers with more than two components, as opposed to prime numbers, which only have one factor, namely 1, and the number itself.
  • All natural numbers that are not prime numbers because they may be split by more than two integers called composite numbers.
  • A composite number is any even number larger than 2.
  • Because it does not have any factors, zero (0) is neither a prime nor a composite number.

Let us consider the first number

7 x 11 x 13 + 13

This can also be written as

(77 + 1) x 13

=1014

The factors of this number are:

13 x 13 x 3 x 2

Since the given number has more than two factors, it is a composite number.

Let us now consider the second number.

7 x 6 x 5 x 4 x 3 x 2 x 1 + 5

This can also be written as

5(7 x 6 x 5 x 4 x 3 x 2 x 1 + 1)

By further calculations, we get:

1009 x 5

Since the given number has more than two factors, it is a composite number.

Hence, proved.