Multiplication and Decimal Delights

Lesson Plan - Get It!

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• Have you ever gone shopping and needed to calculate the total cost of several items?

• Or maybe you've gone for a walk and wondered how far you traveled after a few laps?

Knowing how to multiply decimal numbers can help you solve these kinds of everyday problems!

• What are decimals?

Decimals represent parts of a whole.

Tenths are one part out of ten, such as 0.1.

• How do you multiply two decimals up to the tenths?

Break it down with this example: 2.4 x 3.6

1. Multiply the numbers as whole numbers. Treat 2.4 as 24 and 3.6 as 36.

Example: 24 x 36 = 864

2. Look at the original numbers and count the decimal places.

2.4 has 1 decimal place.

3.6 has 1 decimal place.

Total: 1 + 1 = 2 decimal places

3. Place the decimal in the answer.

Since the total number of decimal places is 2, move the decimal point 2 places to the left in the answer.

Start with 864. Move the decimal point 2 spaces to the left: 8.64.

Final answer: 2.4 x 3.6 = 8.64

Now, look at some example problems to deepen your understanding. Grab some paper and a pencil to show your work for each.

Money Example One

A shirt costs $12.50, and you want to buy 2.3 shirts.

• What's the total cost?

Ignore the decimal points for now and treat the numbers like whole numbers.

125 x 23 = 2875

Now, count how many decimal places were in the original numbers (2 total).

Move the decimal point 2 places to the left.

Final total: $28.75

Money Example Two

A concert ticket costs $13.70, and you're buying 3.1 tickets for you and your friends.

• How much will you spend?

Great work!

Now, try some measurement problems using the same steps.

Measurement Example One

Each window in your classroom is 4.8 feet wide. You need to line up 1.5 windows side by side.

• What is the total width?

Treat the numbers as whole numbers.

48 x 15 = 720

Be sure to place the decimal in the right spot.

That's right! The total width is 7.2 feet.

Try this next problem!

Measurement Example Two

A bike ride around the park is 5.4 miles.

• If you complete 7.3 laps, how far have you gone?

Multiply the laps and determine where to place the decimal in the final answer.

Great job!

Multiplying decimals is a helpful skill for everyday situations like shopping and measuring.

Now that you've practiced multiplying decimals to the tenth place using money and measurements, head to the Got It? section to tackle some exciting new problems!