loga(MN)=logaM+logaN

loga(M/N)=logaM-logaN

logaNn = nlogaN

(N，M，N∈R)

If a=em, then m is the natural logarithm of a, that is, lna=m, e=2.7 1828 1828… is the base of the natural logarithm and is an infinite acyclic decimal. Definition: If an = b(a>；; 0, a≠ 1) Then n=logab.

Log stands for logarithm in high school mathematics.

In general, the function y = logax(a >；; 0, and a≠ 1) is called logarithmic function, that is, a function with power (real number) as independent variable, exponent as dependent variable and base constant as constant is called logarithmic function.

Usually, we call the logarithm with 10 as the common logarithm, and record log 10N as lgN. In addition, the logarithm based on irrational number e=2.7 1828 ... is commonly used in scientific counting, and the logarithm based on e is called natural logarithm, and logeN is recorded as in n.