Find the GCF 63 , 81

$63$ , $81$

Step 1

Find the common factors for the numerical part:

$63, 81$

Step 2

The factors for $63$ are $1, 3, 7, 9, 21, 63$ .

The factors for $63$ are all numbers between $1$ and $63$ , which divide $63$ evenly.

Check numbers between $1$ and $63$

Find the factor pairs of $63$ where $x \cdot y = 63$ .

$\begin{array}{c} x & y \\ 1 & 63 \\ 3 & 21 \\ 7 & 9 \end{array}$

List the factors for $63$ .

$1, 3, 7, 9, 21, 63$

Step 3

The factors for $81$ are $1, 3, 9, 27, 81$ .

The factors for $81$ are all numbers between $1$ and $81$ , which divide $81$ evenly.

Check numbers between $1$ and $81$

Find the factor pairs of $81$ where $x \cdot y = 81$ .

$\begin{array}{c} x & y \\ 1 & 81 \\ 3 & 27 \\ 9 & 9 \end{array}$

List the factors for $81$ .

$1, 3, 9, 27, 81$

Step 4

List all the factors for $63, 81$ to find the common factors.

$63$ : $1, 3, 7, 9, 21, 63$

$81$ : $1, 3, 9, 27, 81$

Step 5

The common factors for $63, 81$ are $1, 3, 9$ .

$1, 3, 9$

Step 6

The GCF (HCF) of the numerical factors $1, 3, 9$ is $9$ .

$9$