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Math

Arithmetic and pre-algebra

The first math topic. Start here if you want to learn the basics (or just want to make sure you know these topics). After this, you should be ready for algebra. This topic includes videos from the former developmental math playlists.
Community Questions
A thumbnail for: Addition and subtraction
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Addition and subtraction

Adding and subtracting positive and negative whole numbers. Starts with 1+1=2 and covers carrying, borrowing, and word problems.
A thumbnail for: Multiplication and division
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Multiplication and division

Multiplying and dividing positive and negative whole numbers, understanding place value, and rounding numbers.
A thumbnail for: Factors and multiples
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Factors and multiples

Understanding and finding factors and multiples. After these videos, you'll be ready for fractions.
A thumbnail for: Negative numbers and absolute value
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Negative numbers and absolute value

Extending our understanding of numbers below 0. Thinking about "absolute" distance from 0.
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Decimals

Understanding decimals conceptually, using operations with decimals, rounding and estimating with decimals, and converting decimals.
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Fractions

Understanding fractions conceptually, using operations with fractions, and converting fractions.
A thumbnail for: Ratios, proportions, units and rates
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Ratios, proportions, units and rates

A thumbnail for: Applying mathematical reasoning
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Applying mathematical reasoning

You already have many tools in your mathematical toolkit. In this topic, you'll use these in settings that you're likely to encounter in the real world!
A thumbnail for: Exponents, radicals, and scientific notation
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Exponents, radicals, and scientific notation

Understanding and solving exponents without algebra.
A thumbnail for: Arithmetic properties
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Arithmetic properties

This tutorial will help us make sure we can go deep on arithmetic. We'll explore various ways to represent whole numbers, place value, order of operations, rounding and various other properties of arithmetic.
A thumbnail for: Telling time
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Telling time

Learn to tell time with some fun exercises!
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Measurement

From length to area to volume to time, thinking about how we measure things.
Negative numbers and absolute value
Extending our understanding of numbers below 0. Thinking about "absolute" distance from 0.

Negative number basics

What is a "negative number"? What happens when I add or subtract one of these? If you come to this tutorial armed with the basics of adding and subtracting numbers, you'll learn about what happens in the world below zero! You will learn what negative numbers are and how we can add and subtract them.

Adding and subtracting negative numbers

You understand that negative numbers represent how far we are "below zero". Now you are ready to add and subtract them! In this tutorial, we will explain, give examples, and give practice adding and subtracting negative numbers. This is a super-important concept for the rest of your mathematical career so, no pressure, learn it as well as you can!

Multiplying and dividing negative numbers

It is starting to dawn on you that negative numbers are incredibly awesome. So awesome that you are feeling embarrassed to think how excited you are about them! Well, the journey is just beginning. In this tutorial we will think about multiplying and dividing numbers throughout the number line!

Absolute value

You'll find absolute value absolutely straightforward--it is just the "distance from zero." If you have a positive number, it is its own absolute value. If you have a negative number, just make it positive to get the absolute value. As you'll see as you develop mathematically, this idea will eventually extend to more contexts and dimensions, so it's super important that you understand this core concept now.