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23 Homework

Exercise 1

Mae had 72 lollipops and wanted to sell packages that had 4 lollipops in each package. How many packages could she make?

a. What division problem do you need to do to find the answer?

b. What model of division does this word problem represent?

c. Explain how to use the correct model to draw a picture to find the answer.

d. Draw a picture using the correct model to help find the answer.

e. Write the multiplication problem shown by the picture:

f. Explain how you use the picture to find the answer to the problem. Be specific.

g. What is the answer to this problem?

Exercise 2

Tina had 72 marbles and wanted to divide them up evenly amongst the 9 children in her class. How many marbles should each child receive?

a. What division problem do you need to do to find the answer? :

b. What model of division does this word problem represent?

c. Explain how to use the correct model to draw a picture to find the answer.

d. Draw a picture using the correct model to help find the answer.

e. Write the multiplication problem shown by the picture:

f. Explain how you use the picture to find the answer to the problem. Be specific.

g. What is the answer to this problem?

Exercise 3

Joan had 12 cups of sugar. A cookie recipe required 2/3 of a cup of sugar. How many recipes could she make?

a. What division problem do you need to do to find the answer? :

b. What model of division does this word problem represent?

c. Explain how to use the correct model to draw a picture to find the answer.

d. Draw a picture using the correct model to help find the answer.

e. Write the multiplication problem shown by the picture:

f. Explain how you use the picture to find the answer to the problem. Be specific.

g. What is the answer to this problem?

Exercise 4

a. Make up a word problem that would require using the partitioning into subsets model of division and the division problem: [latex]20 div 5[/latex].

b. Draw a picture using this model to find the answer.

c. Explain how you use the picture to find the answer to the problem. Be specific.

d. Write the multiplication problem shown by the picture.

e. What is the answer to this problem?

Exercise 5

a. Make up a word problem that would require using the repeated subtraction model of division and the division problem: [latex]20 div 5[/latex].

b. Draw a picture using this model to find the answer.

c. Explain how you use the picture to find the answer to the problem. Be specific.

d. Write the multiplication problem shown by the picture.

e. What is the answer to this problem?

Exercise 6

a. Make up a word problem that would require using the repeated subtraction model of division and the division problem: [latex]6 \div 2/3[/latex].

b. Draw a picture using this model to find the answer.

c. Explain how you use the picture to find the answer to the problem. Be specific.

d. Write the multiplication problem shown by the picture.

e. What is the answer to this problem?

Exercise 7

Draw a picture to do the division [latex]30 div 2[/latex] using

a. partitioning into subsets

b. repeated subtraction.

c. Which model is easiest to draw and why?

Exercise 8

Draw a picture to do the division [latex]32 div 16[/latex] using

a. partitioning into subsets

b. repeated subtraction.

c. Which model is easiest to draw and why?

Exercise 9

Fill in the blanks: [latex]637 \div 14[/latex] = 45 r.7 means [latex]\underline{\qquad}\cdots\underline{\qquad}+\underline{\qquad}=\underline{\qquad}[/latex]

Exercise 10

Someone was solving this problem: “Mark had 42 pencils and wanted to divide them up equally amongst his 3 children. How many pencils should he give each child?”

Which picture best represents a picture he might draw to find the solution?

Picture one shows three circles with 14 inside. Picture two shows fourteen circles with 3 inside.

Exercise 11

To use the division model of “partitioning into subsets”

a. would the number you are dividing by be the number of subsets or the amount in each subset?

b. After doing the division, would the answer be represented by the number of subsets or the amount in each subset?

Exercise 12

To use the division model of “repeated subtraction”,

a. would the number you are dividing by be the number of subsets or the amount in each subset?

b. After doing the division, would the answer be represented by the number of subsets or the amount in each subset?

For problems 13 – 17

a. Divide in the base given using (fast) repeated subtraction. All of your work must be shown. Show ALL steps.

b. Check each answer by multiplying the divisor by the quotient and then adding the remainder to see if this equals the dividend. All of your work must be shown. Do not skip any steps.

Exercise 13

[latex]4320_{\text{seven}} \div 52_{\text{seven}}[/latex]

Exercise 14

[latex]2316_{\text{nine}}\div 7_{\text{nine}}[/latex]

Exercise 15

[latex]60382_{\text{eleven}} \div 21\text{T}_{\text{eleven}}[/latex]

Exercise 16

[latex]43401_{\text{five}} \div 444_{\text{five}}[/latex]

Exercise 17

[latex]2020100_{\text{three}} \div 220_{\text{three}}[/latex]

For problems 18-22

a. Divide in the base given using long division. All of your work must be shown. Show ALL steps.

b. Check each answer by multiplying the divisor by the quotient and then adding the remainder to see if this equals the dividend. All of your work must be shown. Do not skip any steps.

Exercise 18

[latex]2316_{\text{nine}} \div 7_{\text{nine}}[/latex]

Exercise 19

[latex]2316_{\text{eight}} \div 7_{\text{eight}}[/latex]

Exercise 20

[latex]3122_{\text{four}} \div 21_{\text{four}}[/latex]

Exercise 21

[latex]14353_{\text{six}} \div 4_{\text{six}}[/latex]

Exercise 22

[latex]109\text{T}_{\text{twelve}} \div 11_{\text{twelve}}[/latex]

Exercise 23

Decide which of the following sets are closed under division. If it is closed under division, write “closed” and provide at least one example and compelling reason why you are sure it is closed. If it is not closed, write “not closed” and provide a counterexample.

a. {-1} b. {0} c. {0, 1}
d. {-1, 1} e. {1, 2, 3, 4, …}

Exercise 24

Is division commutative?

Support your answer with either an example or a counterexample.

Exercise 25

Is division associative?

Support your answer with either an example or a counterexample

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Math for Elementary Teachers Copyright © by Elizabeth Kelly. All Rights Reserved.