A simple way of approximating π. It is a natural constant. However, it is an irrational number to us. I believe the calculation of π shows the fact that mathematical models can never perfectly represent nature. It is not coincident that nature fits the mathematics. Instead, it is the logically constructed mathematical models can describe the nature sufficiently. Same reasoning that a language has no logics in it. To describe our thoughts in communicable terms, any language will have to arrange words by the logics of our mind. Art, music, words, mathematics, or any form of description is language. We can say universe is musical, artistic, mathematical, and on. Nevertheless, our observation and measurement can only be approximate.