Question

explain 3×5×7+7 is a composite number

Answer 1

A composite number is a number that is divisible by another number other than by itself and one. The number 2 is the only even prime number. All other even numbers are composite numbers.

As per BODMAS rule:

3 x 5 x 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.

Answer 2

Solution:

3 × 5 × 7 + 7 = (3 × 5 + 1) × 7

= (15 + 1) × 7

= 16 × 7 = 7 × 16

Since (3 × 5 × 7 + 7) can be expressed as a

product of primes, it is a composite number