title: Problem 461
date: 2014/03/01 16:00:00
---
***
# [Problem 461](https://projecteuler.net/problem=461)
***
[Xem đề gốc (tiếng Anh)](https://projecteuler.net/problem=461)

## **Gần pi**

$f(n) = \min_{1 \le a,b,c,d \le n} |a/b + c/d - \pi|$. Tính $\sum_{n=1}^{1000} f(n) \times 10^{10}$.

***