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
Addition and subtraction
Adding and subtracting positive and negative whole numbers. Starts with 1+1=2 and covers carrying, borrowing, and word problems.
Multiplication and division
Multiplying and dividing positive and negative whole numbers, understanding place value, and rounding numbers.
Factors and multiples
Understanding and finding factors and multiples. After these videos, you'll be ready for fractions.
Negative numbers and absolute value
Extending our understanding of numbers below 0. Thinking about "absolute" distance from 0.
Understanding decimals conceptually, using operations with decimals, rounding and estimating with decimals, and converting decimals.
Understanding fractions conceptually, using operations with fractions, and converting fractions.
Ratios, proportions, units and rates
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!
Exponents, radicals, and scientific notation
Understanding and solving exponents without algebra.
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.
Learn to tell time with some fun exercises!
From length to area to volume to time, thinking about how we measure things.
Ratios, proportions, units and rates
Would you rather go to a college with a high teacher-to-student ratio or a low one? What about the ratio of girls-to-boys? What is the ratio of eggs to butter in your favorite dessert? Ratios show up EVERYWHERE in life. This tutorial introduces you to what they (and proportions) are and how to make good use of them!
- Introduction to ratios
- Ratios as fractions in simplest form
- Simplifying rates and ratios
- Expressing ratios as fractions
- Describing ratios exercise
- Describing ratios
- Ratio word problem exercise example 1
- Ratio word problem exercise example 2
- Ratio word problems
- Proportion validity example
- Solving ratio problems with tables exercise
- Solving ratio problems with tables exercise 2
- Solving ratio problems with tables exercise 3
- Solving ratio problems with tables
How fast can a robot possum fly? What is the rate at which a hungry you can consume avocados? This tutorial helps you make sense of these fundamental questions in life.
Wait, I'm in Europe and my car only tells my distance traveled in kilometers! But I'm used to a units of distance devised by the Romans to measure the average length of 1000 paces of a soldier (the "mile")! How do I operate? This tutorial is about the fundamental skill of unit conversion. Sal's cousin Nadia being a bit confused with this was actually the reason why he started tutoring her (which led to the creation of the Khan Academy).
- Converting pounds to ounces
- Converting gallons to quarts, pints, and cups
- Converting yards into inches
- Performing arithmetic calculations on units of volume
- Safe elevator
- Blood drive
- Gas cost for a roadtrip
- Squirrel survival
- Running laps
- Unit conversion example: Drug dosage
- Unit conversion with fractions
- Speed translation
If you're American, you might be surprised to realize that the rest of the world doesn't use feet, miles, or yards or a bunch of other "English System" conventions (the irony being that the English don't even use the "English System" any more). Most everyone else, including the English, now use the metric system which is actually much more logical. So be prepared to learn about kilo and milli and centi and become a metric unit megastar!
There are three major conventions for measuring temperature in the world, Farenheit, Celsius and Kelvin. If converting between the three gives you cold feet, then this tutorial might warm them up.