1、log(a) (M N)=log(a) M+log(a) N

2、log(a) (M÷N)=log(a) M-log(a) N

Log (m n = nlog (a)

4、log(a)b*log(b)a= 1

log(a) b=log (c) b÷log (c) a

Extended data

Discovery of logarithm:

At the turn of 16 and 17 century, with the development of astronomy, navigation, engineering, trade and military, it is urgent to improve the digital calculation method. John Napier (J. Napier, 1550~ 16 17) invented logarithm to simplify the calculation in astronomy. The invention of logarithm is an important event in the history of mathematics, and the astronomical community is almost ecstatic about this invention.

Engels once called the invention of logarithm, the establishment of analytic geometry and the establishment of calculus1the three major achievements of mathematics in the 7th century. Galileo also said, "Give me space, time and logarithm, and I can create a universe."