# Problem 1 Multiples of 3 or 5

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.

# 思路分析

## 优化思路

1000 以内 k 的倍数和为

$$\large \frac{\left (1000-1 \right)}{k}$$

# 代码实现

## 优化思路

Thank you for your support to Jason ~