Lesson 2.7Dividing by a Decimal
Start hereWords, worked example, and sentence starters
Learning target I can divide with decimals by making the divisor a whole number first.
Start hereWords for this lesson
Read each word before you begin. Say it out loud.
| Word | What it means | Example |
|---|---|---|
| DividendSpanish: Dividendo | The total number being divided into equal groups (the number inside the division bracket). | In 8.4 ÷ 0.2, it is 8.4 |
| DivisorSpanish: Divisor | The number of equal groups you are dividing into (the number outside the division bracket). | In 8.4 ÷ 0.2, it is 0.2 |
| QuotientSpanish: Cociente | The answer when you divide. | 8.4 ÷ 0.2 = 42 |
| Decimal Division AlgorithmSpanish: Algoritmo de división decimal | The steps for dividing decimals: slide the divisor's decimal point right until the divisor is a whole number, slide the dividend's point right the same number of places, then divide. | 8.4 ÷ 2.1 → move the point in both → 84 ÷ 21 → divide, multiply, subtract, bring down → 4 |
| Equivalent divisionSpanish: División equivalente | Multiplying both numbers by 10 or 100 gives the same answer. | 8.4 ÷ 0.2 → 84 ÷ 2 |
| Annex a zeroSpanish: Agregar un cero | Write a zero after the last decimal digit without changing the value. | 7.2 → 7.20 |
How it worksWorked examplemaking the divisor a whole number
These numbers are not on your problems. The steps are. Follow them with your own numbers.
How many 0.4-liter cups can be filled from 9.6 liters of juice?
- The divisor 0.4 is not whole, so slide its point one place right to make it 4.
- Slide the dividend's point the same one place: 9.6 becomes 96.
- Divide the equivalent problem 96 ÷ 4 with the usual algorithm.
- Sliding both points multiplies both numbers by ten, so the quotient does not change.
Answer: 24 cups can be filled, because 9.6 ÷ 0.4 and 96 ÷ 4 have the same quotient.
Now you trySame steps, your turn
The steps are the same as the worked example. The numbers are yours. Do the work.
How many 0.25-meter ribbons can be cut from 8.5 meters of ribbon?
- Is the divisor whole? Slide its point places right to get
- Slide the dividend the same number of places:
- Divide the new whole-number problem: ÷
- Number of ribbons: Check by multiplying.
Say it and write itSentence starters
Finish each sentence out loud with a partner. Then use them in your writing.
- The divisor is not a whole number, so I slid its point places.
- I slid the dividend the same way, turning into .
- The equivalent problem is ÷ .
- The quotient stays the same because .
Word bank divisordividendquotientslidedecimal pointequivalentpower of tenwhole numberplacesestimatecheckmultiply
Watch outA common mistake
A common mistake in Divide Decimals is moving the decimal point in the divisor but forgetting to move it the same number of places in the dividend. For example, in 6.4 ÷ 0.8 a student changes 0.8 to 8 but leaves the dividend as 6.4, then divides 6.4 ÷ 8 = 0.8 instead of moving both points to get 64 ÷ 8 = 8. A second version of this mistake happens when the divisor has two decimal places, like 0.12: students move both points only 1 place instead of 2, turning 9.6 ÷ 0.12 into 96 ÷ 1.2 instead of the correct 960 ÷ 12. Count the divisor's decimal places first, then move BOTH points that same number of places.
Lesson 2.7Dividing by a Decimal
Apply Day · Version ASupported practice
Learning target I can divide with decimals by making the divisor a whole number first.
-
1Complete each step, then write the final answer.
Find 4.2 ÷ 0.6.
Show your workHint Move both points 1 place right. Then find 42 ÷ 6.
Final answer: -
2Complete each step, then write the final answer.
Find 12.5 ÷ 2.5.
Show your workHint Move both points 1 place right. Then find 125 ÷ 25.
Final answer:
-
3Complete each step, then write the final answer.
A rope is 3.2 meters long. Each piece is 0.4 meter long. How many pieces can you cut?
Show your workHint Move both points 1 place right. Then find 32 ÷ 4.
Final answer:
Lesson 2.7Dividing by a Decimal
Apply Day · Version BCore practice
Learning target I can divide with decimals by making the divisor a whole number first.
-
1Complete each step, then write the final answer.
Find 0.84 ÷ 0.07.
Show your workFinal answer: -
2Complete each step, then write the final answer.
Find 9.6 ÷ 0.8.
Show your workFinal answer:
-
3Complete each step, then write the final answer.
Leo finds 4.8 ÷ 0.6. He moves the point in 0.6 but not in 4.8. He gets 0.8. What is the correct quotient?
Show your workFinal answer:
Lesson 2.7Dividing by a Decimal
Apply Day · ChallengeExtension
Learning target I can divide with decimals by making the divisor a whole number first.
-
1Complete each step, then write the final answer.
Find 2.8 ÷ 0.35.
Show your workFinal answer:
-
2Circle the letter of the best answer. Show how you know.
Find 18.9 ÷ 6.3 using the decimal division algorithm.
- A0.3
- B2.8
- C3
- D30
Show your work -
3Complete each step, then write the final answer.
Ana says 6.3 ÷ 0.07 is 9. She changed the problem to 63 ÷ 7. What is the correct quotient?
Show your workFinal answer: