圆周率纪念日（三月１４日）就要到了，大家庆祝一番

In 1910, the Indian mathematician Srinivasa Ramanujan found several rapidly converging infinite series of π, including

1π=229801∑k=0∞(4k)!(1103+26390k)(k!)43964k

which computes a further eight decimal places of π with each term in the series. His series are now the basis for the fastest algorithms currently used to calculate π. Evaluating the first term alone yields a value correct to seven decimal places:

π≈980122062≈3.14159273