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 $\,1\,.$