E is a very important constant in mathematics. It is the base of natural logarithm, usually written as e, and its value is about 7 1828, which is an infinite cycle decimal. E was first discovered by mathematician John Napier in17th century. It has important applications in various branches of mathematics such as calculus, number theory and statistics.

The definition of e comes from the definition of natural logarithm, which is a logarithmic function based on e, expressed by ln x or log e x, and represents the natural logarithm of x, where x is a positive real number. The value of e can be calculated by infinite series, that is, e =1+11! + 1/2! + 1/3! +...+ 1/n！ +...。

The meaning of e is very important in mathematics. It is used to represent compound functions, differential equations and series in calculus, and it is also an important concept in compound interest calculation and probability theory. Through E, we can better understand various problems in mathematics and further discover the beauty of mathematics. Therefore, understanding and mastering the concept and calculation method of E is very important for learning and studying mathematics.