Sometimes a logarithm is written without a base, like this: This usually means that the base is really 10. It is called a "common logarithm". Engineers love to use it. On a calculator it is the "log" button.

In mathematics, the logarithm of a number is the exponent by which another fixed value, the base, must be raised to produce that number. For example, the logarithm of 1000 to base 10 is 3, because 1000 …

Can't log in? Use your email address as your username. Password not working? Click Forgot your password? Are you a parent with a home account? Login here

Learning with Zearn helps math make sense. Students explore math through pictures, visual models, and real-life examples. Log in to your Zearn account.

Are you a student looking to study mathematics on your own, and want to do exercises with immediate feedback as you work through a free and open textbook? Then read more about our self study courses.

Imagine Math and Imagine Math Facts support students and teachers with personalized, interactive math instructions for grades PreK through High School.

MyLab® Math gives you the tools to easily customize your course and guide students to real results.