10-NEM-Gr4-Chap10
7/19/03
12:54 PM
Page 266
CHAPTER 10
You will need
2
Using Repeated
Subtraction to Divide
• counters
Goal Use repeated subtraction to divide.
Zola is making decorations for a banquet.
She is tying balloons together in bunches of 4.
? How many bunches of 4 balloons can Zola
make with 77 balloons?
Zola’s Division
I can model the balloons with 77 counters.
Then I can use repeated subtraction to subtract
bunches of 4 until there aren’t enough balloons to
make any more bunches.
47
7
- 40
37
– ■■
I start with 77 balloons.
10
5
I can make at least 10 bunches
because 10 x 4 = 40.
Now I have 37 balloons left.
I can make 5 more bunches because …
A. Why does Zola think she can make 5 bunches next?
Show how you would continue Zola’s recording to
complete the division.
B. How many bunches of 4 balloons can Zola make in all?
Explain how you know.
C. What will the remainder be? Explain how you know.
266
remainder
The number left
over after an
amount is divided
into equal parts
When you divide
7 into 3 groups,
you get 2 in each
group and a
remainder of 1.
Write 7 3 2 R1
remainder
NEL
10-NEM-Gr4-Chap10
7/19/03
12:54 PM
Page 267
Reflecting
1. Why did Zola start by subtracting 10 groups of 4?
2. When Zola had 37 balloons left, she decided to
subtract 5 bunches. Was this the quickest way
to finish the division? Explain your answer.
3. Why does it make sense to subtract multiples
of 4 to find out how many 4s there are in 77?
multiples
The products
when a number
is multiplied by
other numbers
The multiples
of 4 are 4, 8, 12,
16, 20, 24, ….
Checking
4. Zola has 99 balloons to put in bunches of 6.
a) How many bunches could she subtract first?
Why? How many balloons would that be?
b) How many bunches can she make in all?
Show all your steps.
c) What will the remainder be? Explain how you know.
Practising
5. Zola has 62 balloons to put in bunches of 5.
How many bunches can she make?
What will the remainder be?
Show your steps.
6. Use repeated subtraction to divide. Show your steps.
a) 36
4
b) 45
0
c) 66
2
d) 29
5
e) 48
7
7. Zola used a calculator to solve 441 21.
She used pencil and paper to solve 96 8.
Do you agree with Zola’s choice of methods?
Explain your answer.
8. Zola had about 70 balloons. When she made groups
of 4 balloons, she had no balloons left over.
How many balloons could Zola have had?
Explain how you know.
NEL
267