Question

Explain whether 3 x 12 x 101 +4

Answer 1

Any prime number is divisible by either 1 or itself. Thus, if we can prove that the given number is divisible by any number other than 1 and the number itself then it would mean that it's a composite number.
$3 \times 12 \times 101 + 4 \\ = 4(3 \times 3 \times 101) \\ = 4 \times 909$
We see that the given number is divisible by 4, which is not equal to 1. Thus, the given number is a composite number.