3. Multiplication and division

Lesson

Knowing your times tables is an ideal way to move on to other ways to solve multiplication problems.

Find 8 \times 3.

Worked Solution

Idea summary

We can use our times tables, arrays or skip counting to find products.

Let's see how we use the partition, array, and area method to multiply 2 digit numbers by 1 digit numbers, then see how we could use an algorithm to solve our problem.

Let's use an area model to find 77 \times 3.

a

Fill in the areas of each rectangle.

Worked Solution

b

What is the total area of all four rectangles?

Worked Solution

c

Find 77 \times 3.

Worked Solution

Idea summary

We have different ways we can solve multiplication problems, such as the area method and arrays. But as our numbers get larger, the algorithm method can be more useful.

We can also use the strategies we've seen above to multiply larger numbers, so let's see how the area method can be used. Then we solve the same problem, using a vertical algorithm. Which do you prefer?

Find 6178 \times 4.

Worked Solution

Idea summary

We can use several different methods to solve multiplication problems, but we don't always know if we will need to do any regrouping or trading. If we use an algorithm, regrouping can be done as we solve our problem.