We know how to solve equations such as or by thinking about integer powers of 10. The solutions are and . What about an equation such as ?

Because and , we know that is between 2 and 3. We can use a logarithm to represent the exact solution to this equation and write it as:

The expression  is read “the log, base 10, of 250.”

• The small, slightly lowered “10” refers to the base of 10.
• The 250 is the value of the power of 10.
• is the value of the exponent that makes equal 250.

In the specific case where the base of the logarithm is 10, the “log” can be written without the number 10. For example, can also be written as , and this expression is read “the log of 250.”

One way to estimate logarithms is with a logarithm table. For example, using this base 10 logarithm table we can see that is between 2.3010 and 2.4771.