Give the value of each digit in 5.39.

5 wholes, 3 tenths, and 9 hundredths

What is another way to name 56 hundredths?

Every 10 hundredths can be regrouped as 1 tenth. So, 56 hundredths is 5 tenths and 6 hundredths.

What is another way to name 48 tenths?

Every 10 tenths can be regrouped as 1 whole. So, 48 tenths is 4 wholes and 8 tenths.

Describe how to solve 63 &#247 9.

If I divide 63 wholes equally among 9 groups, each group has 7 wholes. 63 &#247 9 = 7.

How can you use estimation to check if 58 × 32 = 1,856 makes sense?

I can round 58 to 60, and 32 to 30. 60 × 30 is 1,800, which is close to 1,856. This is how I know my answer makes sense.

If you are calculating 3.64 – 2.14, which number should you represent using the fraction square model? What is the second step?

The greater number, 3.64. Then, take away blocks that represent 2.14 in total.

You want to calculate 3.4 – 0.8. You represent 3.4 using 3 wholes and 4 tenths. What else do you need to do before you can subtract 8 tenths?

I don’t have enough tenths to subtract 8 tenths, so I need to regroup 1 of the wholes as 10 tenths. Then, I have 2 wholes and 14 tenths. Now I can subtract 8 tenths from 14 tenths. The answer is what remains, 2 wholes and 6 tenths, or 2.6.

How can you use skip counting to multiply 6 × 1.4?

1.4 means 1 whole and 4 tenths. I need to multiply each number by 6, which is the same as skip counting sixes. 6 × 1 = 6. 6 × 4 tenths = 24 tenths. 24 tenths is the same as 2 wholes and 4 tenths, so altogether I have 8 wholes and 4 tenths, or 8.4.

Mimi multiplies 4 by 2 wholes, 3 tenths, and 7 hundredths and gets 8 wholes, 12 tenths, and 28 hundredths. Is that the final answer?

No, Mimi needs to do some regrouping, starting with the smallest place, the hundredths place. 28 hundredths can be regrouped as 2 tenths and 8 hundredths. So, now there are 8 wholes, 12 + 2 = 14 tenths, and 8 hundredths. Next, regroup some of the tenths. 10 tenths can be regrouped as 1 whole, so the final answer is 9 wholes, 4 tenths, and 8 hundredths, or 9.48.

What can you do to check if 3.8 × 5.1 = 19.38 makes sense?

I can round 3.8 to 4 and 5.1 to 5. Multiply: 4 × 5 = 20. 20 is close to 19.38, so the answer makes sense.

Solve Problems with Decimals (Using Models)

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What you will learn from this videoWhat you will learn

We’ll add, subtract, multiply and divide decimals using models.
We will also learn how to use estimation to decide if our answer is reasonable.
And that this knowledge can help us feed our pets, go hiking and even grow crystals!

Discussion Questions
- Before Video
  Give the value of each digit in 5.39.ANSWER
  - 5 wholes, 3 tenths, and 9 hundredths
  What is another way to name 56 hundredths?ANSWER
  - Every 10 hundredths can be regrouped as 1 tenth. So, 56 hundredths is 5 tenths and 6 hundredths.
  What is another way to name 48 tenths?ANSWER
  - Every 10 tenths can be regrouped as 1 whole. So, 48 tenths is 4 wholes and 8 tenths.
  Describe how to solve 63 ÷ 9. ANSWER
  - If I divide 63 wholes equally among 9 groups, each group has 7 wholes. 63 ÷ 9 = 7.
  How can you use estimation to check if 58 × 32 = 1,856 makes sense?ANSWER
  - I can round 58 to 60, and 32 to 30. 60 × 30 is 1,800, which is close to 1,856. This is how I know my answer makes sense.
- After Video
  If you are calculating 3.64 – 2.14, which number should you represent using the fraction square model? What is the second step? ANSWER
  - The greater number, 3.64. Then, take away blocks that represent 2.14 in total.
  You want to calculate 3.4 – 0.8. You represent 3.4 using 3 wholes and 4 tenths. What else do you need to do before you can subtract 8 tenths?ANSWER
  - I don’t have enough tenths to subtract 8 tenths, so I need to regroup 1 of the wholes as 10 tenths. Then, I have 2 wholes and 14 tenths. Now I can subtract 8 tenths from 14 tenths. The answer is what remains, 2 wholes and 6 tenths, or 2.6.
  How can you use skip counting to multiply 6 × 1.4? ANSWER
  - 1.4 means 1 whole and 4 tenths. I need to multiply each number by 6, which is the same as skip counting sixes. 6 × 1 = 6. 6 × 4 tenths = 24 tenths. 24 tenths is the same as 2 wholes and 4 tenths, so altogether I have 8 wholes and 4 tenths, or 8.4.
  Mimi multiplies 4 by 2 wholes, 3 tenths, and 7 hundredths and gets 8 wholes, 12 tenths, and 28 hundredths. Is that the final answer?ANSWER
  - No, Mimi needs to do some regrouping, starting with the smallest place, the hundredths place. 28 hundredths can be regrouped as 2 tenths and 8 hundredths. So, now there are 8 wholes, 12 + 2 = 14 tenths, and 8 hundredths. Next, regroup some of the tenths. 10 tenths can be regrouped as 1 whole, so the final answer is 9 wholes, 4 tenths, and 8 hundredths, or 9.48.
  What can you do to check if 3.8 × 5.1 = 19.38 makes sense?ANSWER
  - I can round 3.8 to 4 and 5.1 to 5. Multiply: 4 × 5 = 20. 20 is close to 19.38, so the answer makes sense.
Vocabulary
- Place value DEFINE
- Decimals DEFINE
- Ones place DEFINE
- Tenths place DEFINE
- Hundredths place DEFINE
- Models DEFINE
- Regroup DEFINE
Reading Material
Practice Word Problems
Practice Number Problems
Lesson Plan
Teacher Guide
Assessment
Online Quiz Game Quiz PDF Exit Ticket