Practice with Multiples
The multiples of $\,2\,$ are $\,2\,,$ $\,4\,,$ $\,6\,,$ $\,8\,,$ $\,10\,,$ $\,12\,,$ $\,14\,,$ $\,16\,,$ $\,18\,,$ and so on.
Notice that the multiples of $\,2\,$ are obtained by taking the number $\,2\,,$ and multiplying successively by $\,1\,,$ $\,2\,,$ $\,3\,,$ $\,\ldots\,$ Notice also that $\,2\,$ goes into each of these numbers evenly.
The multiples of $\,3\,$ are $\,3\,,$ $\,6\,,$ $\,9\,,$ $\,12\,,$ $\,15\,,$ $\,18\,,$ $\,21\,,$ $\,24\,,$ $\,27\,,$ and so on.
Notice that the multiples of $\,3\,$ are obtained by taking the number $\,3\,,$ and multiplying successively by $\,1\,,$ $\,2\,,$ $\,3\,,$ $\,\ldots\,$ Notice also that $\,3\,$ goes into each of these numbers evenly.
In general, the multiples of a number $\,\,x\,\,$ are $\,\,x\,,$ $\,\,2x\,,$ $\,\,3x\,,$ $\,\,4x\,,$ and so on. To test if something is a multiple of $\,\,x\,,$ just see if $\,\,x\,\,$ goes into it evenly.