# Practice with Factors

In this discussion,
*number* refers to a counting number:
$\,1\,$, $\,2\,$, $\,3\,$, and so on.

The *factors* of a number are
the numbers that go into it evenly.

For example, the factors of $\,10\,$ are $\,1\,$, $\,2\,$, $\,5\,$, and $\,10\,$.

The factors of $\,42\,$ are $\,1\,$, $\,2\,$, $\,3\,$, $\,6\,$, $\,7\,$, $\,14\,$, $\,21\,$, and $\,42\,$.

Notice that factors occur in pairs:

$1\times 42 = 42$

$2\times 21 = 42$

$3\times 14 = 42$

$6\times 7 = 42$

Every number has a factor of $\,1\,$, because $\,1\,$ goes into everything evenly. Also, every number has itself as a factor. Thus, the number $\,1\,$ has only one factor—itself. Every other number has at least two factors—itself and $\,1\,$.