Khan Academy
Khan Academy is an organization on a mission. We're a notforprofit with the goal of changing education for the better by providing a free worldclass education for anyone anywhere.
All of the site's resources are available to anyone. It doesn't matter if you are a student, teacher, homeschooler, principal, adult returning to the classroom after 20 years, or a friendly alien just trying to get a leg up in earthly biology. Khan Academy's materials and resources are available to you completely free of charge.
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Adding and subtracting is the basis of all mathematics. This tutorial introduces you to onedigit addition and subtraction. You might become pretty familiar with the number line too!

Learn what those are shortly) so you can see that adding or subtracting two digit numbers is really just an extension of what you already know.
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Preteen, Teen, Adult
In this tutorial, we'll start adding and subtracting numbers that have two (yes, two!) digits. We won't be doing any carrying or borrowing (you'll learn what those are shortly) so you can see that adding or subtracting two digit numbers is really just an extension of what you already know.

Introduce you to the powerful tool of carrying and why it works.
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Preteen, Teen, Adult
You're somewhat familar with adding, say, 17+12 or 21+32, but what happens for 13+19? Essentially, what happens when I max out the "ones place". In this tutorial, we'll introduce you to the powerful tool of carrying and why it works.

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Preteen, Teen, Adult
You can subtract 21 from 45, but are a bit perplexed trying to subtract 26 from 45 (how do you subtract the 6 in 26 from the 5 in 45). This tutorial is your answer. You'll see that we can essentially "regroup" the value in a number from one place to another to solve your problem. This is also often called borrowing (although it is like "borrowing" sugar from your neighbor in that you never give it back).

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You feel comfortable with adding and subtracting multidigit numbers. Now you can apply some of your skills to solve problems that arise in the real world (often called "word problems").

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Preteen, Teen, Adult
If 3 kids each have two robot possums, how many total robot possums do we have?;You liked addition, but now you're ready to go to the next level. Depending on how you view it, multiplication is about repeated addition or scaling a number or seeing what number you get when you have another number multiple times. If that last sentence made little sense, you might enjoy this tutorial.

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Preteen, Teen, Adult
Every time you split your avocado harvest with your 10 pet robot possums, you've been dividing. You don't farm avocados? You only have 8 robot possums? No worries. I'm sure you've divided as well.;Multiplication is awesome, but you're ready for the next step. Division is the art of trying to split things into equal groups. Like subtraction undoes addition, division also undoes multiplication. After this tutorial, you'll have a basic understanding of all of the core operations in arithmetic!

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Preteen, Teen, Adult
Math is super useful in the real world. In this tutorial, we'll get some practice figuring out things that would have been tough without the powerful tools of multiplication and division!

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Preteen, Teen, Adult
The distributive property is an idea that shows up over and over again in mathematics. It is the idea that 5 x (3 + 4) = (5 x 3) + (5 x 4). If that last statement made complete sense, no need to watch this tutorial. If it didn't or you don't know why it's true, then this tutorial might be a good way to pass the time:)

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Preteen, Teen, Adult
If you have the expression "3 + 4 x 5", do you add the 3 to the 4 first or multiply the 4 and 5 first? To clear up confusion here, the math world has defined which operation should get priority over others. This is super important. You won't really be able to do any involved math if you don't get this clear. But don't worry, this tutorial has your back.

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 Science & Math: Biology
 Science & Math: Algebra
 Science & Math: Arithmetic & Mathematics
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 Science & Math: Physics
 Science & Math: Addition, Subtraction, Multiplication & Division
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