美国现在流通中的磁条信用卡和储值卡超过50亿张，我们可以用这个数字乘以3美元。

Multiply $3 by the more than 5 billion magstripe credit and prepaid cards in circulation in the U.S.

youdao

本：我们可以用这个。

BEN: We can use this.

youdao

我们可以用这个定理来解决很多问题。

We can use that fact to solve lots of problems.

youdao

And we can calculate that with the formula that we used, which was just n minus l minus 1 equals the number of nodes.

这个我们可以用我们以前用过的那个公式来计算，也就是节点数等于ｎ减去ｌ减去１

麻省理工公开课 - 化学原理课程节选

Again we can look at this in terms of thinking about a picture this way, in terms of drawing the wave function out on an axis.

同样我们可以,用这个图像来考虑，从画轴上的波函数来考虑。

麻省理工公开课 - 化学原理课程节选

So now we have this derivative, in terms of physical quantities, things that we can measure.

现在我们得到了这个导数,它可以用实验可测的与。

麻省理工公开课 - 热力学与动力学课程节选