Find the GCF 10 , 20 , 40

$10$ , $20$ , $40$

Find the common factors for the numerical part:

$10, 20, 40$

The factors for $10$ are $1, 2, 5, 10$ .

The factors for $10$ are all numbers between $1$ and $10$ , which divide $10$ evenly.

Check numbers between $1$ and $10$

Find the factor pairs of $10$ where $x \cdot y = 10$ .

$\begin{array}{c} x & y \\ 1 & 10 \\ 2 & 5 \end{array}$

List the factors for $10$ .

$1, 2, 5, 10$

The factors for $20$ are $1, 2, 4, 5, 10, 20$ .

The factors for $20$ are all numbers between $1$ and $20$ , which divide $20$ evenly.

Check numbers between $1$ and $20$

Find the factor pairs of $20$ where $x \cdot y = 20$ .

$\begin{array}{c} x & y \\ 1 & 20 \\ 2 & 10 \\ 4 & 5 \end{array}$

List the factors for $20$ .

$1, 2, 4, 5, 10, 20$

The factors for $40$ are $1, 2, 4, 5, 8, 10, 20, 40$ .

The factors for $40$ are all numbers between $1$ and $40$ , which divide $40$ evenly.

Check numbers between $1$ and $40$

Find the factor pairs of $40$ where $x \cdot y = 40$ .

$\begin{array}{c} x & y \\ 1 & 40 \\ 2 & 20 \\ 4 & 10 \\ 5 & 8 \end{array}$

List the factors for $40$ .

$1, 2, 4, 5, 8, 10, 20, 40$

List all the factors for $10, 20, 40$ to find the common factors.

$10$ : $1, 2, 5, 10$

$20$ : $1, 2, 4, 5, 10, 20$

$40$ : $1, 2, 4, 5, 8, 10, 20, 40$

The common factors for $10, 20, 40$ are $1, 2, 5, 10$ .

$1, 2, 5, 10$

The GCF (HCF) of the numerical factors $1, 2, 5, 10$ is $10$ .

$10$