A mathematical function used to derive an exponent of a base number, i.e. ${\log }_{b}x=y\iff b^y=x$. The base number is typically 2 in computer science, e in physics and 10 in e.g. economics and social sciences. Logarithms make it possible to present a multiplication as an addition instead, e.g. $a\times b=c$ becomes $\log (a)+\log (b)=\log (c)$. Most natural scales, e.g. the Richter scale, are logarithmic.