3. Multiplication and division

Lesson

Division is related to multiplication, so solving multiplication problems helps us when we need to solve division problems.

Find 6178 \times 4.

Worked Solution

Idea summary

If we use an algorithm, regrouping can be done as we solve our problem.

Let's see how we can use area models and arrays to work out division problems, numbers up to hundreds.

Let's use an area model to find the answer to 45 \div 3.

a

We set up the area model using a rectangle like this:

We don't know what 45\div3 is straight away, we start with something we do know, like 30\div 3.

Find the area used so far if we take out 10 groups of 3.

Worked Solution

b

How much area is remaining?

Worked Solution

c

What is the width of the second rectangle?

Worked Solution

d

Using the area model above, what is 45\div3?

Worked Solution

Idea summary

We can use area models to divide one number by another number.

We can use what we know about place value and partitioning numbers to solve division problems as well, as we see in this video.

Find the value of 396 \div 3.

Worked Solution

Idea summary

We can divide large numbers by partitioning the number, and then dividing each part of the partition.

We can use a vertical algorithm to solve division, and it helps when we work with larger numbers, as this video shows.

Find the value of 856 \div 8.

Worked Solution

Idea summary

Division is when we share a total into a number of groups, or find out how many items each group has. It is the reverse of multiplication.

selects and applies appropriate strategies for multiplication and division, and applies the order of operations to calculations involving more than one operation