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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.
A thumbnail for: Decimals
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Decimals

Understanding decimals conceptually, using operations with decimals, rounding and estimating with decimals, and converting decimals.
A thumbnail for: Fractions
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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!
A thumbnail for: Measurement
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Measurement

From length to area to volume to time, thinking about how we measure things.
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!

Multi-step word problems

The world seldom gives you two numbers and tells you which operation to perform. More likely, you'll be presented with a bunch of information and you (yes, YOU) need to make sense of them. This tutorial gives you practice doing exactly that. When watching videos, pause and attempt it before Sal. Then work on as many problems as you want in the exercise at the end of the tutorial.

Inequalties : Greater than and less than basics

Equality is usually a good thing, but the world is not a perfect place. No matter how hard we try, we can't help but compare one thing to another and realize how unequal they may be. This tutorial gives you the tools to do these comparisons in the mathematical world (which we call inequalities). You'll become familiar with the "greater than" and "less than symbols" and learn to use them.

Cross topic arithmetic

You've probably been learning how to do arithmetic for some time and feel pretty good about it. This tutorial will make you feel even better once by showing you a bunch of examples of where it can be applied (using multiple skills at a time). Get through the exercises here and you really are an arithmetic rock star!

Constructing numeric expressions

Let's construct and interpret expressions from word problems. We can also think about what the effects of parentheses are.