Numbers and operations

This course is a part of 8th grade, a 7-course Topic series from Khan Academy.

Math is all about numbers (like 89 and 3.14) and operations (like addition and multiplication). In these tutorials, we learn about a some new types of numbers and some new types of operations.

This course contains 12 segments:

Repeating decimals

Learn how to convert between repeating decimals and fractions.

Square roots & cube roots

A strong contender for coolest symbol in mathematics is the radical. What is it? How does it relate to exponents? How is the square root different than the cube root? Learn all about square roots and cube roots in this tutorial.

Irrational numbers

Learn what irrational numbers are. Also learn how to classify numbers as whole, integer, rational, and irrational.

Approximating irrational numbers

The values of irrational numbers can't be written perfectly as decimals or fractions. However, we can approximate them, which is usually good enough. In this tutorial, we learn how to approximate and compare irrational numbers.

Exponents with negative bases

Evaluate exponential expressions with negative bases, use odd and even rules to determine the sign of an exponential expression, and learn about powers of 1 and 0.

Exponent properties intro

Learn the rules for simplifying exponent expressions.

Negative exponents

It's normally a bad idea to hang around with negative people or do negative things, but we think it's OK to associate with negative exponents. As a matter of fact, we'll learn that positive and negative exponents have quite the opposite effect on their bases.

Exponent properties (integer exponents)

Practice using the exponent properties to rewrite powers, where the exponent can either be positive or negative.

Working with powers of 10

This tutorial leads in to scientific notation. It features multiplication and division problems involving powers of 10.

Scientific notation intro

Scientists and engineers often deal with super huge numbers like 6,000,000,000,000,000,000,000 and super small numbers like 0.0000000000532. How can they do this without tiring their hands out? How can they look at a number and understand how large or small it is without counting the digits? The answer to both questions: scientific notation.

Arithmetic with numbers in scientific notation

Solve multiplication, division, addition, and subtraction problems involving numbers written in scientific notation.

Scientific notation word problems

Solve word problems involving scientific notation.