Australian Curriculum - Multiply decimals by whole numbers and perform divisions by non-zero whole numbers where the results are terminating decimals, with and without digital technologies (ACMNA129)

Watch the video http://splash.abc.net.au/media/-/m/29700

In the real world, people need to have an understanding or how to multiply decimals by whole numbers. By knowing how to do this, as in the case of petrol, it could save them a lot of money.

Think about this problem 3 x 5 It is the same as saying 3 lots of 5 or 5 + 5 + 5

We need to extend the same thinking to when we multiply a whole number such as 4 and a decimal such as 0.3

What are some other ways we could describe this number sentence 4 x 0.3?

Watch the video http://splash.abc.net.au/media/-/m/29700

In the real world, people need to have an understanding or how to multiply decimals by whole numbers. By knowing how to do this, as in the case of petrol, it could save them a lot of money.

Think about this problem 3 x 5 It is the same as saying 3 lots of 5 or 5 + 5 + 5

We need to extend the same thinking to when we multiply a whole number such as 4 and a decimal such as 0.3

What are some other ways we could describe this number sentence 4 x 0.3?

## To Multiply a Decimal

- Ignore the decimal point and multiply the digits

- Place the decimal point in the answer so that it has the same number of decimal places as the number being multiplie

Calculate 1.7 × 2 =

17 x 2 = 34 Ignore the decimal point and multiply the digits.

34 ➝ 3.4 There is one decimal place in the decimal number being multiplied. So, we place the decimal

point one place from the right-hand end of the answer.

Calculate 45.27 × 6

Note : There are two decimal places in the decimal number being multiplied. So, we place the decimal point two places from the right-hand end of the answer.

Calculate 7.382 × 5

Calculate 7.382 × 5

Note: There are three decimal places in the decimal number being multiplied. So, we place the decimal point three places from the right-hand end of the answer.

Any trailing zeros in the decimal places of the answer can be omitted.

View the PDF HERE. Copy the questions into your workbook and calculate the answer.

Once you have finished HERE are some word problems to practice which require you to multiply decimals with whole numbers. Write the information you need into your workbook to help you answer the questions.

Your job is to find how much money you would need to spend to fill up all three vehicles at various petrol stations around Landsdale and the Perth area. You will need to record your information in a chart (log into EDMODO and download the chart - the group code is 4vabi9) .

The chart needs will include the following information - what date you retrieved your information, which petrol station you are at, which suburb, how much the price is for diesel and unleaded fuel, and how much each vehicle costs to fill up, and the total amount of money spent.

We can use the information to decide which petrol station our family should go to. Here is the link to Fuelwatch.

Any trailing zeros in the decimal places of the answer can be omitted.

View the PDF HERE. Copy the questions into your workbook and calculate the answer.

Once you have finished HERE are some word problems to practice which require you to multiply decimals with whole numbers. Write the information you need into your workbook to help you answer the questions.

**Extension**: Your family has two cars and one motorbike. The first car has a petrol tank which can hold 55 litres of**unleaded petro**l . The second car has a tank that holds 83 litres of**Diesel**. The motorbike has a tank that can hold 17 litres**of unleaded petrol (UL)**.Your job is to find how much money you would need to spend to fill up all three vehicles at various petrol stations around Landsdale and the Perth area. You will need to record your information in a chart (log into EDMODO and download the chart - the group code is 4vabi9) .

The chart needs will include the following information - what date you retrieved your information, which petrol station you are at, which suburb, how much the price is for diesel and unleaded fuel, and how much each vehicle costs to fill up, and the total amount of money spent.

We can use the information to decide which petrol station our family should go to. Here is the link to Fuelwatch.