# 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 $\,1\,.$