In classes that use a lot of decimals -- usually science -- you're almost always allowed to use a calculator, so you won't have to be able to do this by hand for long!
How to Multiply Decimals (free)
This video covers all the basics of multiplying decimals, by whole numbers and by other decimals. Sometimes we'll have to put in extra zeroes, other times we'll just move the decimal around, but mostly it's just like multiplying whole numbers.
How to Divide Decimals
Long division of decimals is a lot like long division of whole numbers. The main difference is that sometimes you'll move a decimal around, or need to tack on some extra 0's to the end of the number, so this video will cover all that stuff!
How To Round Decimals
Whether you're in pre-algebra or College Chemistry, rounding decimals is something that you can't afford to mess up. So if you have trouble with this, in this video I'll show you the sure-fire way to not mess up, and how to avoid the most common mistake I see.
Converting REPEATING Decimals to Fractions
You need equations and variables to convert repeating decimals to fractions, so if you're not there yet in class, skip this video. But if you're ready for this topic, it's definitely one of the only fun things you'll do in algebra. Most of my students, even ones who hate math, enjoy working these problems because... I don't know why, maybe because it feels like you're outsmarting your calculator?7.NS.1, 7.NS.2, 7.NS.3
If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)