To help you understand the algorithm, the video shows a simple two-digit by two-digit multiplication. You can see that the first and last digits are essentially the result of one multiplication.

It's not enough for a student to be able to divide one fraction by another. He or she must also "use the relationship between multiplication and division to explain that (2/3) ÷ (3/4) = 8/9 ...

The Common Core State Standards teach students the algorithm for multi-digit addition and subtraction in 4th grade. But some experts say it should be taught sooner.