143 is a composite number.
A prime number is defined as a natural number greater than 1 that has no positive divisors other than 1 and itself. In contrast, a composite number is a natural number that has at least one positive divisor other than 1 and itself.
To determine whether 143 is prime or composite, we can check its divisibility by smaller prime numbers. When we test for divisibility by 2, 3, 5, 7, 11, and 13, we find:
- 143 is odd, so it’s not divisible by 2.
- The sum of the digits (1 + 4 + 3) equals 8, which is not divisible by 3.
- 143 does not end in 0 or 5, so it’s not divisible by 5.
- Dividing 143 by 7 gives approximately 20.43, which is not an integer.
- Dividing 143 by 11 gives approximately 13, so 11 is a divisor.
- Also, 143 divided by 13 gives approximately 11, showing that both 11 and 13 are factors.
Since 143 has divisors other than 1 and itself (it can be factored as 11 x 13), we conclude that 143 is indeed a composite number.