Logarithmic formula is a common formula in mathematics. If ax = n (a >; 0, and a≠ 1), then x is called the logarithm of n with a as the base, and is recorded as x=log(a)(N), where a should be written in the lower right of log. Where a is called the base of logarithm and n is called real number. Usually, we call the logarithm with the base of 10 as the ordinary logarithm, and the logarithm with the base of e as the natural logarithm.

means of expression

(1) Common logarithm: LG (b) = log 10b (10 as the base).

(2) natural logarithm: ln (b) = logeb (e as the base).

E is an infinite acyclic decimal, usually only e=2.7 1828.