How to Factor Numbers

“Factors” are the numbers we multiply to get another number. In this post learn how to factor numbers easily.

Step by step guide to factoring numbers

• Factoring numbers means breaking the numbers into their prime factors.
• First few prime numbers: $$2, 3, 5, 7, 11, 13, 17, 19$$
• To factor a number, start with the smallest prime number which is $$2$$. Is the number divisible by $$2$$? If so, divide it by $$2$$ and do the same for the result. If not, check the next prime number which is $$3$$, and do the same process.

Factoring Numbers – Example 1:

List all positive factors of $$8$$.

Solution:

Write the upside-down division: $$8$$ is divisible by $$2$$. Then:

The first column shows all the factors of number $$8$$.
Then: $$8=2 \ \times \ 2 \ \times \ 2$$ or $$8=2^{3}$$

All factors of $$8$$ are: $$1, 2, 4, 8$$

Factoring Numbers – Example 2:

List all positive factors of $$24$$.

Solution:

Write the upside-down division:

The second column is the answer.
Then: $$24= 2 \ \times \ 2 \ \times \ 2 \ \times \ 3$$
or $$24=2^{3} \ \times \ 3$$

All factors of $$24$$ are: $$1, 2, 3, 4, 6, 8, 12, and 24$$

Factoring Numbers – Example 3:

List all positive factors of $$12$$.

Solution:

Write the upside-down division:

The second column is the answer.
Then: $$12=2×2×3$$
or $$12=2^2×3$$

All factors of $$12$$ are: $$1, 2, 3, 4, 6, 12$$

Factoring Numbers – Example 4:

List all positive factors of $$20$$.

Solution:

Write the upside-down division:

Write the upside-down division:
The second column is the answer.
Then: $$20=2×2×5$$ or $$20=2^2×5$$

All factors of $$20$$ are: $$1, 2, 4, 5, 10, and 20$$

Exercises for Factoring Numbers –

List all positive factors of each number.

1. $$\color{blue}{68}$$
2. $$\color{blue}{56}$$
3. $$\color{blue}{24}$$
4. $$\color{blue}{40}$$
5. $$\color{blue}{86}$$
6. $$\color{blue}{78}$$

1. $$\color{blue}{1, 2, 4, 17, 34, 68}$$
2. $$\color{blue}{1, 2, 4, 7, 8, 14, 28, 56}$$
3. $$\color{blue}{1, 2, 3, 4, 6, 8, 12, 24}$$
4. $$\color{blue}{1, 2, 4, 5, 8, 10, 20, 40}$$
5. $$\color{blue}{ 1, 2, 43, 86 }$$
6. $$\color{blue}{ 1, 2, 3, 6, 13, 26, 39, 78 }$$

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