Instead of adding up the same number over and over again, try using multiplication. If you buy 6 bags of popcorn for $2.00 each, you would multiply.
6 x 2 = 12
It would cost you $12.00

So, we need a review of how to multiply larger numbers, right? Watch the video and practice.

If you are having trouble viewing this Youtube video, click on the following link instead:

Multiplication - Khan Academy

Now, practice your skills using the following online quiz:

Multiplication Quiz - Khan Academy

Here's another method that may be helpful to some of you.