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What are all the factors, the prime factorization, and factor pairs of 18?

To find the factors of 18, divide 18 by each number starting with 1 and working up to 18

Now let us find how to calculate all the factors of 18:
2
= 9
3
= 6
As you can see, the factors of 18 are:
1, 2, 3, 6, 9, 18

Introduction to Factors

Factors are foundational elements in mathematics, which, when multiplied together, result in a given number. Using 18 as an illustrative example, we explore what these factors are and why they are significant. Factors help in understanding the structure and properties of 18, offering insights into division, multiplication, and number theory.

What are Factors of 18?

The concept of factors for 18 reflects the whole numbers that evenly divide 18, leaving no remainder. Below is a visual representation and tabular list of factors and their pairings as seen in the multiplication process:

• 1 x 18 = 18
• 2 x 9 = 18
• 3 x 6 = 18

Therefore, the complete list of factors of 18 is 1, 2, 3, 6, 9, and 18.

How to Find the Factors of 18?

Finding the factors of 18 can be done using the division method, which we can illustrate step-by-step:

To find the factors of 18, start by dividing 18 by integers starting from 1 up to 18. If the division results in a whole number, then the divisor is a factor of 18.

• 18 ÷ 1 = 18
• 18 ÷ 2 = 9
• 18 ÷ 3 = 6
• 18 ÷ 6 = 3
• 18 ÷ 9 = 2
• 18 ÷ 18 = 1

Thus, the factors we discover through this method are 1, 2, 3, 6, 9, and 18.

Pair Factors of 18

Pair factors of 18 are two numbers that, when multiplied together, equal 18. Here we list both positive and negative pair factors:

Positive Pair Factors Negative Pair Factors
1 x 18 -1 x -18
2 x 9 -2 x -9
3 x 6 -3 x -6

Prime Factorization of 18

For the number 18, prime factorization is accomplished by dividing 18 by the smallest prime numbers until only 1 remains. Here’s a factor tree diagram to illustrate:

• 18 ÷ 2 = 9
• 9 ÷ 3 = 3
• 3 ÷ 3 = 1

Prime factorization of 18 is therefore 2 x 3 x 3, or 2 x 3².

Important Points to Remember

The key points about the factors of 18 include the following insights:

• The total count of factors for 18 is six.
• The prime factors of 18 are 2 and 3.
• Pair factors of 18 include (1, 18), (2, 9), and (3, 6).
• The sum of all factors of 18 (1+2+3+6+9+18) is 39.

Exercises

Test your understanding of the factors of 18 with these questions:

1. How many factors does 18 have?
2. List all the factors of 18.
3. What are the prime factors of 18?

Solutions to Exercises

1. 18 has six factors: 1, 2, 3, 6, 9, and 18.
2. The factors of 18 are 1, 2, 3, 6, 9, and 18.
3. The prime factors of 18 are 2 and 3.

What are the factors of 18?

The factors of 18 are the numbers 1, 2, 3, 6, 9, and 18.

Is 18 a prime number?

No, 18 is not a prime number; it has factors other than 1 and itself.

How is the prime factorization of 18 represented?

The prime factorization of 18 is represented as 2 x 3².