參考資料來源:https://medium.com/%E7%A8%8B%E5%BC%8F%E4%B9%BE%E8%B2%A8/python-round-%E5%9B%9B%E6%8D%A8%E4%BA%94%E5%85%A5-%E7%9A%84%E5%B0%8F%E5%9D%91-7ef8accad931
簡單來說,因為電腦是2進位,1.5其實是1.499…