# Interactive Logarithm Table

Before calculators, the best way to do arithmetic with large (or small) numbers was using log tables.

Invented in the early 1600s century by John Napier, log tables were a crucial tool for every mathematician for over 350 years.

First, let's find some log values and see what they mean when re-expressed in index notation.

## Find the log of a number

Your calculator has only base 10 or base e logarithms. The following section allows you find the log of whatever number you like, for some common bases.

Log Values, Different Bases

decimal places

The logarithm of (base ) is .

That is:

In index notation, the above log equation means the same as:

The above calculator is using the Change of Base formula that we met earlier.

## Interactive Log Table

In this next section, you can create different sized log tables, with different bases.

By exploring the values given in the tables, you can better understand how logs work. For example, when the base is 2, the log of 8 is 3.0000. This is simply because 2^3=8. Logarithms are just index expressions written sideways, after all.

Table of Log Values

decimal places