A scientific calculator has two 'log' buttons on it. These are marked log and ln. The log key is used for calculations of the form \({\log _{10}}x\). For example, to work out that \(\log 10000 = 4 ...

Now that you know what \({\log _a}x\) means, you should know and be able to use the following results, known as the laws of logarithms.