Composite numbers

What is a composite number?

A composite number is any number which has more than two factors.

Examples of composite numbers

4 (factors: 1, 2, 4)
6 (factors: 1, 2, 3, 6)
9 (factors: 1, 3, 9)
15 (factors: 1, 3, 5, 15)
100 (factors: 1, 2, 4, 5, 10, 20, 25, 50, 100)

Non-examples of composite numbers

2 (factors: 1, 2) - only two factors, so it is prime
3 (factors: 1, 3) - only two factors, so it is prime
5 (factors: 1, 5) - only two factors, so it is prime
29 (factors: 1, 29) - only two factors, so it is prime
97 (factors: 1, 97) - only two factors, so it is prime
1 (factors: 1) - only one factor, so it is neither prime nor composite

Prime numbers

You may think that all non-composite numbers are prime numbers, and you’d be right… usually.

The number 1 has only one factor: 1, so it is not composite because it does not have more than 2 factors.
It is also not prime, because prime numbers have exactly 2 factors.

flashcards

Question	Answer
What is a composite number?	A number with more than two factors.
Give an example of a composite number and list its factors	4 (factors: 1, 2, 4)
Give an example of a composite number and list its factors	6 (factors: 1, 2, 3, 6)
Give an example of a composite number and list its factors	9 (factors: 1, 3, 9)
Give an example of a composite number and list its factors	15 (factors: 1, 3, 5, 15)
Give an example of a composite number and list its factors	100 (factors: 1, 2, 4, 5, 10, 20, 25, 50, 100)
Why is 2 not a composite number?	It has only two factors (1, 2), so it is prime.
Why is 3 not a composite number?	It has only two factors (1, 3), so it is prime.
Why is 5 not a composite number?	It has only two factors (1, 5), so it is prime.
Why is 29 not a composite number?	It has only two factors (1, 29), so it is prime.
Why is 97 not a composite number?	It has only two factors (1, 97), so it is prime.
Why is 1 not a composite number or a prime number?	It has only one factor (1), so it is neither prime nor composite.
How many factors does a prime number have?	A prime number has exactly two factors.
How many factors does the number 1 have?	The number 1 has only one factor.