Multiplication & Division of Large Numbers

What this lesson covers

Multiplication & Division of Large Numbers is a 9-part Class 5 Mathematics lesson. Each part makes one point and then hands over to the next, so it can be read in a sitting or picked up again at the part you stopped on. It defines the idea in plain words before using it, works through an example step by step, breaks the topic into its parts and compares them, shows where it is used outside the textbook, names the mistakes that cost marks in an exam, ends with a recap of what to remember.

How it begins

Nothing new happens when numbers get large. You are still using the tables you know, just applying them one place at a time and keeping track of place value. The difficulty in long multiplication and division is almost never the arithmetic. It is organisation: keeping columns straight and remembering what each digit is worth.

The 9 parts

1. Big numbers, same rules
2. Splitting is the underlying idea
3. Long multiplication, step by step
4. Long division, step by step
5. Estimating first
6. Where large numbers come up
7. Where it usually goes wrong
8. What to remember
9. Watch one worked through