Question

Is 143 a prime number

Answer 1

Not because 143 is divided by 11 and by 13.

143 = 13 × 11

143 has 4 divisors:

{ 1, 11, 13, 143}

The prime number has only 2 divisors: 1 and itself.

Answer 2

143 is composite. To be prime it has to have only 2 divisors i.e it's self and one but since it has 4 divisors ( 143, 1, 11 and 13) it is composite.