iOS/Android/Desktop: Default calculator apps suck. They work like a traditional handheld calculator, which only displays one value at a time and can only do basic math. If you want to do anything more ...

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 \(\log 10000 = 4\) ...