It just throws the decimal point away and that's because, again, these are ints and the answer intuitively should be a floating point value, but I need to be more specific.

它直接把小数点后面的数值丢弃掉了，因为，凭直觉，那些整型数和结果应该是一个浮点数据,但是我需要一个更精确的数值。

哈佛公开课 - 计算机科学课程节选