The answer is--this goes way back-- it's an old tradition and they used to have to do this by hand.

答案要追溯到很久之前,这是个古老的传统,他们过去用手工计算

耶鲁公开课 - 金融市场课程节选

So if you've ever seen or used an old school typewriter, you might recall that when you're typing something out on an old mechanical typewriter, - when you like hit the char-- when you hit the enter key to move the head back to the left hand side to the next line or you would pull down some lever, it was really a two part process.

如果你们有谁曾经看过或用过老式打字机，可能还记得，当你在,这种老式打字机上打字的时候，当你-,敲入回车键，跳转到,下一行的最左边，或者,拉一下杆，这个需要两步走。

哈佛公开课 - 计算机科学课程节选

And so this time when you hand it back, this value, I store it in -- we'll say X, and now we actually have retained the value.

这次当你拿回这个值时，我把它存储在X中，现在我们把这个值保存了。

哈佛公开课 - 计算机科学课程节选