To add numbers, you can line up the numbers vertically and then add the matching places together. This tutorial shows you how to add numbers vertically!
Multiplying integers is just like performing a bunch of additions of the same integer! Check out this tutorial and see how much multiplying and repeated addition have in common.
Ratios are everywhere! The scale on a map or blueprint is a ratio. Ingredients sometimes need to be mixed using ratios such as the ratio of water to cement mix when making cement. Watch this tutorial to learn about ratios. Then think of some ratios you've encountered before!