In mathematics, lg stands for logarithm with the base of 10, which is also called ordinary logarithm. Logarithmic function is a basic elementary function, which is used to describe the inverse operation of exponential operation. A number n can be expressed as the x power of a (where a >；; 0 and a≠ 1), then the logarithm of n based on a is the number x, and it is recorded as x=logaN. In lg function, the base a is 10, and lgN represents the logarithm of n with the base 10. This function is usually used to solve exponential and logarithmic problems in mathematics and science.