# How do you use the Change of Base Formula and a calculator to evaluate log_7 648?

Nov 27, 2015

$\log \frac{648}{\log} 7$

#### Explanation:

${\log}_{a} b = \log \frac{b}{\log} a$

Notice that there is a $\log$ button on your calculator.

${\log}_{7} 648 = \log \frac{648}{\log} 7$

Put this into your calculator as "log(648)/log(7)"—don't forget the parentheses.