The second important limit was first put forward by German mathematician Karl Weierstrass. The formula is: lim (1+(1/x)) x = e (x →∞), where e is the base of natural logarithm, which is about 2.7 1828.

This limit formula plays an important role in calculus and real analysis, revealing the internal relationship between exponential function and logarithmic function, and opening up a new field of vision for subsequent mathematical research.