multiply-divide

基本解释

Simple math tool to practice add, subtra - Simple math tool to practice add, subtract, multiply, and divide.
簡單的數學工具用來執行加，減，乘，除運算。
Where they fared less well was number ability (how quickly you can multiply, add, subtract and divide) and perceptual speed - how fast you can push a button when prompted.
年長者表現不太好的方麪則是：（數字能力加減乘除運算的速度）以及感知速度——聽到指令按下按鈕的速度。
So, the number of nuclei, 119 if we were to sit and count these as well, is 119. So, we'll multiply that by just pi, r squared, to get that cross-section, and divide all of that by 1 .
如果你們數的話，原子核的數是，我們用它乘以πr的平方，得到橫截麪積，除以1。

So, the number of nuclei, 119 if we were to sit and count these as well, is 119. So, we'll multiply that by just pi, r squared, to get that cross-section, and divide all of that by 1 . 39 meters squared.
如果你們數的話，原子核的數是，我們用它乘以πr的平方，得到橫截麪積，除以1。39平方米。
麻省理工公開課 - 化學原理課程節選