Which number is composite?

Which number is composite?

• A. 2
• B. 4
• C. 3
• D. 5

Answer: (B)

Composite numbers are positive integers greater than 1 that can be written as a product of two integers both greater than 1. That means they have a divisor other than 1 and themselves. The number 4 fits this because it equals 2 × 2, so it has a nontrivial factorization. The other numbers cannot be factored into smaller integers besides 1 and themselves, so they are prime. Therefore, the composite number here is 4.

Composite numbers are positive integers greater than 1 that can be written as a product of two integers both greater than 1. That means they have a divisor other than 1 and themselves. The number 4 fits this because it equals 2 × 2, so it has a nontrivial factorization. The other numbers cannot be factored into smaller integers besides 1 and themselves, so they are prime. Therefore, the composite number here is 4.