The logarithmic symbol "log" was first introduced by Leibniz in mathematics books. Its original source comes from the first three letters of Latin logaritus, and the further abbreviation lg stands for logarithm with 10 as the base, that is, common logarithm. Commonly used logarithm is also called Briggs logarithm. If the irrational number e is taken as the base, c = 2.718 281.828 459 045 ... = natural logarithm, represented by the symbol "ln", introduced by Euler and synthesized by Latin anturalis and Latin logitumus.