92093147.F Multiplication Student
92093147.F Multiplication Student
92093147.F Multiplication Student
Series
Student
Multiplication
and Division
My name
Copyright © 2009 3P Learning. All rights reserved.
First edition printed 2009 in Australia.
A catalogue record for this book is available from 3P Learning Ltd.
ISBN 978-1-921860-78-2
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Series F – Multiplication and Division
Contents
Topic 1 – Mental multiplication strategies (pp. 1–10) Date completed
• doubling strategy_______________________________________ / /
• split strategy__________________________________________ / /
• compensation strategy__________________________________ / /
• halving strategy________________________________________ / /
• split strategy__________________________________________ / /
• tests of divisibility______________________________________ / /
• extended multiplication__________________________________ / /
• short division__________________________________________ / /
• solving problems_______________________________________ / /
• bugs – investigate______________________________________ / /
• puzzles – apply_________________________________________ / /
Series Authors:
Rachel Flenley
Nicola Herringer
Copyright ©
Mental multiplication strategies – doubling strategy
a b c
2 40
1 4 10 20 6 12
3 6 15 30 9 24
D D D
5 9 25 40 96 8
2 7 35 50 32 16
a 4 8
__________ 16
___________ __________ 64
___________ __________
c 5 __________ ___________ 40
__________ ___________ __________
d 25 50
__________ ___________ __________ ___________ __________
e 7 __________ 28
___________ __________ ___________ 224
__________
f 75 __________ 300
___________ __________ ___________ __________
3 Choose a number and create your own doubling pattern. How high can you go? What patterns can you
see within your pattern?
4 Two sets of twins turn 12. They decide to have a joint birthday party with 1 giant cake but they all want
their own candles. How many candles will they need?
SERIES TOPIC
Mental multiplication strategies – doubling strategy
5 Use the doubling strategy to solve these:
To multiply by 4, double
×2 ×4 twice. To multiply by 8,
double three times.
a 13 × 4 26
___________ 52
___________
b 16 × 4 ___________ ___________
c 24 × 4 ___________ ___________
d 25 × 4 ___________ ___________
e 32 × 4 ___________ ___________
f 21 × 4 ___________ ___________
g 35 × 4 ___________ ___________
×2 ×4 ×8
a 12 × 8 24
_____________ ____________ 96
____________
d 21 × 8 _____________ 84
____________ ____________
f 16 × 8 32
_____________ ____________ ____________
7 Work out the answers in your head using the appropriate doubling strategy. Use a table like the one
above if it helps.
a 18 × 4 = b 16 × 4 = c 26 × 4 =
d 24 × 8 = e 15 × 8 = f 22 × 8 =
8 Nick’s dad offered him two methods of payment for helping with a 5 week landscaping project.
When we multiply by 10 we move the number one place value to the left.
When we multiply by 100 we move the number two place values to the left.
When we multiply by 1 000 we move the number three place values to the left.
Look at how this works with the number 45:
a T Th Th H T U b T Th Th H T U
1 7 4 3
× 10 × 10
× 100 × 100
× 1 000 × 1 000
c T Th Th H T U d T Th Th H T U
8 5 9 9
× 10 × 10
× 100 × 100
× 1 000 × 1 000
2 Try these:
a 14 × 10 = b 14 × 100 = c 14 × 1 000 =
d 92 × 10 = e 92 × 1 000 = f 92 × 100 =
g 11 × 1 000 = h 11 × 100 = i 11 × 10 =
3 You’ll need a partner and a calculator for this activity. Take turns giving each other problems such as
�Show me 100 × 678�. The person whose turn it is to solve the problem, writes down their prediction
and you both check it on the calculator. 10 points for each correct answer, and the first person to
50 points wins.
SERIES TOPIC
Mental multiplication strategies – multiply by 10s, 100s and 1 000s
It is also handy to know how to multiply multiples of 10 such as 20 or 200 in our heads.
4 × 2 helps us work out 4 × 20: 4 × 2 = 8 4 × 20 = 80
We can express this as 4 × 2 × 10 = 80 How would you work out 4 × 200?
b Huy earns $20 pocket money per week. If he saves half of this, how much
will he have saved at the end of 8 weeks?
c The sum of two numbers is 28. When you multiply them together, the
answer is 160. What are the numbers?
a 10 20 30
__________ __________ ___________ 60
__________
b 20 40 __________ 80
__________ ___________ __________
c 30 60 __________ __________ 150
___________ __________
d 40 80 __________ __________ 200
___________ 240
__________
e 50 100 150
__________ __________ ___________ __________
f 100 200 __________ 400
__________ ___________ __________
g 200 400 __________ __________ ___________ 1 200
__________
Sometimes it’s easier to split a number into parts and work with the parts separately.
Look at 64 × 8
Split the number into 60 and 4
Work out (60 × 8) and then (4 × 8)
Add the answers together 480 + 32 = 512
a 46 × 4 b 74 × 5 c 48 × 4
= = =
d 37 × 7 e 62 × 8 f 91 × 5
(___ × ___) + (___ × ___) (___ × ___) + (___ × ___) (___ × ___) + (___ × ___)
= = =
2 Use the split strategy to answer the questions. This time see if you can do the brackets in your head:
c 9 × 43 = __________ + __________ =
d 8 × 29 = __________ + __________ =
e 86 × 7 = __________ + __________ =
3 These problems have been worked out incorrectly. Circle where it all went wrong.
a 37 × 6 b 17 × 5 c 32 × 9
(30 × 6 ) + (7 × 6) (10 × 5) + (7 × 5) (30 × 9) + (2 × 9)
180 + 13 70 + 35 27 + 18
= 193 = 105 = 45
SERIES TOPIC
Mental multiplication strategies – split strategy
4 Each trail contains 2 multiplication problems and steps to solve them. Only one trail has been solved
correctly. There are errors in the other two. Find and colour the winning trail.
FINISH
78
291 114
13 × 6 33 × 9 16 × 9
464 294 51
(40 × 7) + (2 × 7) 400 + 64 30 + 21
42 × 7 58 × 8 17 × 3
START
1 Use the compensation strategy to answer the questions. The first one has been done for you.
20
a 19 × 3 = ________ 3
× ________ 3
– ________ = 57
2 Use the compensation strategy and adjust up for these. The first one has been done for you.
SERIES TOPIC
Mental multiplication strategies – compensation strategy
3 In this activity you’ll work alongside a partner. You’ll each need two dice and your own copy
of this page. For each line, roll the dice to find the tens digit and then roll it again to find the
multiplier. Your partner will do the same. Use the compensation strategy to mentally work
out the answers to the problems. copy
Tens Units Multiplier Answer
1 × =
9 × =
2 × =
1 × =
8 × =
1 × =
9 × =
8 × =
2 × =
1 × =
a 18 b 25
c 14 d 9
e 16 f 15
g 30 h 42
2 Fill the gaps in these sentences. The first one has been done for you.
1 or _____
a _____ 16 or _____
2 or _____
8 or _____
4 people can share 16 lollies evenly.
b _____ or _____ or _____ or _____ or _____ or _____ people can share 20 slices of pie evenly.
c _____ or _____ or _____ or _____ or _____ or _____ or _____ or _____ people can share 24 cherries.
d _____ or _____ or _____ or _____ or _____ or _____ or _____ or _____ people can share 30 pencils.
3 Use a calculator to help you find as many factors of 384 as you can:
SERIES TOPIC
Mental multiplication strategies – factors and multiples
a 4 b 5 c 9 d 7
8 10
16
35
63
Numbers can be either factors or multiples depending on where they sit in the number sentence.
5 Choose 2 numbers between 2 and 5 and put them in the first frame as factors. Your answer is the
multiple. Now take that multiple and make it a factor in another number sentence. Write in the other
factor and solve the problem. Then make the answer a factor again. Can you fill the grid? Use a calculator
for the larger problems. The first one has been done for you.
a 3 × 4 = 12 12 × 2 = 24 24 × 2 = 48
b × = × = × =
c × = × = × =
d × = × = × =
Knowing our multiplication facts helps us with division as they do the reverse of each other.
They are inverse operations.
3 × 5 = 15 15 ÷ 5 = 3
1 Use your knowledge of multiplication facts to help answer these division questions:
a 56 ÷ 7 8
________ × 7 = 56 56 ÷ 7 =
c 72 ÷ 8 ________ × 8 = 72 72 ÷ 8 =
d 49 ÷ 7 ________ × 7 = 49 49 ÷ 7 =
e 36 ÷ 9 ________ × 9 = 36 36 ÷ 9 =
f 64 ÷ 8 ________ × 8 = 64 64 ÷ 8 =
g 36 ÷ 4 = h 45 ÷ 9 =
i 39 ÷ 3 = j 24 ÷ 6 =
a b c
36 24 81 9 36 16
60 6 54 18 28 40
÷6 ÷9 ÷4
42 48 72 36 44 24
30 18 63 45 32 8
SERIES TOPIC
Mental division strategies – use multiplication facts
4 Complete the following patterns. How many more multiplication and division facts can you find, given the
first fact?
a 7 × 8 = 56 b 8 × 9 = 72 c 7 × 9 = 63
8 × 7 = 9 × 8 = 9 × 7 =
56 ÷ = 8 72 ÷ =9 63 ÷ = 9
÷ 8 = 7 ÷ 9 = 8 ÷ 9 = 7
5 Write down another multiplication fact and two division facts for each question.
a 6 × 7 = 42 b 5 × 9 = 45 c 9 × 6 = 54
d 17 × 8 = 136 e 12 × 8 = 96 f 11 × 21 = 231
Imagine you’re explaining to a younger child how they’re related yet different. How would you do it?
What would you say/write/draw?
When we divide by 10 we move the number one place value to the right.
When we divide by 100 we move the number two place values to the right.
When we divide by 1 000 we move the number three place values to the right.
Look what happens to 45 000 when we apply these rules:
a T Th Th H T U b T Th Th H T U
4 5 0 0 0 4 3 0 0 0
÷ 10 ÷ 10
÷ 100 ÷ 100
÷ 1 000 ÷ 1 000
c T Th Th H T U d T Th Th H T U
8 5 0 0 0 8 8 0 0 0
÷ 10 ÷ 10
÷ 100 ÷ 100
÷ 1 000 ÷ 1 000
SERIES TOPIC
Mental division strategies – halving strategy
When the two numbers seem too large to work with in our heads, we can halve them till we get to
a division fact we recognise. Both numbers must be even for this to work.
126 ÷ 14
(half 126) ÷ (half 14)
63 ÷ 7 = 9
1 Practise your halving. The first one has been done for you.
a 32 16 b 24 c 50
56 48 500
36
halve
72
halve
1 000
halve
84 144 250
96 192 100
2 Halve each number to get to a recognisable division fact. The first one has been done for you.
a 112 ÷ 14 56
________ 7
÷ ________ = 8
c 96 ÷ 12 ________ ÷ ________ =
3 Match the problems with their halved equivalents. Then solve the problem. The first one has been done
for you.
a 90 ÷ 18 60 ÷ 6 = 5
b 64 ÷ 16 24 ÷ 8 =
c 120 ÷ 12 35 ÷ 7 =
d 70 ÷ 14 45 ÷ 9 =
e 144 ÷ 24 72 ÷ 12 =
f 48 ÷ 16 32 ÷ 8 =
4 Keep halving until you get to a fact you can work with. If you can do it in your head, just fill in the last
box. Otherwise, use the lines to help you.
5 Draw lines to connect numbers that could be doubled or halved to reach each other.
10 16
48 40
32 25 64
20
60 96
30
128
256 192
120
125 250
50
80
100
SERIES TOPIC
Mental division strategies – split strategy
Division problems also become easier if you split the number to be divided into recognisable facts.
Look at the problem 144 ÷ 9 144 ÷ 9
1 Use the split strategy to divide these numbers. Use the clues to guide you:
a 112 ÷ 8 b 85 ÷ 5 c 78 ÷ 6
80
_____ 32
_____ 50
_____ _____ 18
_____ _____
÷ 8 ÷8 ÷ 5 ÷5 ÷ 6 ÷6
_____ + _____ = 7
_____ + _____ = 10 + _____ =
_____
d 64 ÷ 4 e 91 ÷ 7 f 144 ÷ 8
24
_____ _____ 21
_____ _____ 80
_____ 64
_____
÷ 4 ÷4 ÷ 7 ÷7 ÷ 8 ÷8
______ ÷ ______
c 72 ÷ 4 =
24 ÷ ______
______
______ ÷ ______
d 144 ÷ 8 =
96 ÷ ______
______
96 ÷ 4 45 90
75 ÷ 5 25 21
87 ÷ 3 60 50
98 ÷ 7 80 70
135 ÷ 9 55 36
78 ÷ 6 30 60
112 ÷ 8 60 60
51 ÷ 3 27 32
95 ÷ 5 24 40
84 ÷ 6 28 18
Multiplication and Division
Copyright © 3P Learning
F 2 17
SERIES TOPIC
Mental division strategies – tests of divisibility
Divisibility tests tell us if a number can be divided evenly by another (that is with no remainders).
1 Use the rules to test out the numbers in the last column. The first two have been done for you:
Is 7 281 divisible by 3?
Is 3 912 divisible by 4?
Is 455 divisible by 5?
Is 74 160 divisible by 8?
Is 6 345 divisible by 9?
36 90 84 99 50 72
456 330 888 120 981 548
1 025 3 486 6 993 1 256 9 050 10 072
÷4 ÷5
÷9 ÷3
÷8
SERIES TOPIC
Written methods – contracted multiplication
e: e: e:
a H T U b H T U c H T U
3 2 7 2 4 7 1 5 4
× 3 × 4 × 5
e: e: e:
d H T U e H T U f H T U
3 1 5 2 8 6 1 9 4
× 3 × 2 × 5
2 Solve these word problems. Show how you worked them out:
Jess Harry
1 1 1 1
3 8 7 3 8 7
× 2 × 2
7 7 4 7 7 4
1 6
1 1 9 1 1 9
× 7 × 7
7 7 3 8 3 3
2 0 3 2 0 3
× 3 × 3
6 0 9 6 9
1 1 1
4 3 6 4 3 6
× 3 × 3
1 2 0 8 1 3 0 8
4 0 1 4 0 1
× 7 × 7
2 8 0 7 2 8 7
SERIES TOPIC
Written methods – extended multiplication
H T U
2 3 4
× 3 Extended multiplication is another way of solving
problems. In extended multiplication we multiply
1 2 (3 × 4)
the units, tens and hundreds separately then add
9 0 (3 × 30)
the answers together.
6 0 0 (3 × 200)
7 0 2
1 Use a calculator to help you work out the values you could expect when
2 × 2 would give
multiplying the following. Tick the columns: me a unit only. But
8 × 6 would give me
T TH TH H T U tens and units. I’ll
tick both columns.
a a unit by a unit 9 × 7
b a ten by a unit 43 × 5
d a ten by a ten 13 × 72
e: e: e:
a 2 4 5 b 4 5 2 c 3 2 7
× 2 × 7 × 8
(2 × 5) (7 × 2) (8 × 7)
(2 × 40) (7 × 50) (8 × 20)
(2 × 200) (7 × 400) (8 × 300)
e: e:
d 2 7 9 e 4 1 2
× 2 × 9
(2 × _____) (9 × _____)
(2 × _____) (9 × _____)
(2 × _____) (9 × _____)
a Jack and his 2 friends bought tickets to the b Jack has a paper round and earns $7 per day. He
World Cup. Each ticket costs $124. How much works for 18 days and saves it all. Has he earned
did they spend altogether? enough to pay for his World Cup ticket?
e: e:
c Yusuf’s highest Level 1 Live Mathletics score is d Kyra’s class of 24 all had to stay in for 11 minutes
112. Yep, he’s fast. If he scores this 7 times in a of their recess. Something to do with too much
row, how many correct answers has he achieved? talking. How many minutes is this in total?
e: e:
4 Once you have the hang of extended multiplication, you can apply it to larger numbers. Try these:
a 2 4 5 b 3 2 9 c 2 3 8
× 3 2 × 4 3 × 5 2
(2 × 5) (3 × 9) (2 × 8)
SERIES TOPIC
Written methods – short division
In short division, we use our knowledge of multiplication to help us. We can split 936 into 900 + 30 + 6.
900 divided by 3 is 300, so we put a 3 in the hundreds place.
3 1 2
30 divided by 3 is 10, so we put a 1 in the tens place.
3 9 3 6 6 divided by 3 is 2, so we put a 2 in the units place. 936 ÷ 3 = 312
a b c
4 8 4 5 5 5 3 9 3
d e f
9 9 9 0 4 4 8 4 6 6 6 6
g h i
3 9 9 9 2 4 6 2 3 6 9 3
2 Decide how you’ll split these numbers and then divide. Remember
to put in zeros as needed.
a b
5 5 1 5 3 6 6 9
c d e
9 9 2 7 4 8 0 4 4 8 1 2
Sometimes numbers don’t divide evenly. The amount left over is called the remainder.
Look at 527 divided by 5.
500 divided by 5 is 100.
1 0 5 r2
27 divided by 5 is 5 with 2 left over (this is the remainder).
5 5 2 7
This can be written as r 2.
527 ÷ 5 = 105 r 2.
a r b r c r
9 7 5 4 4 7 6 3 8
d r e r f r
5 6 3 4 4 9 6 6 2
a r b r c r
5 5 5 7 3 6 6 1 4 4 8 1
d r e r f r
9 9 9 4 4 8 4 5 6 6 3 8
___________________________________________________________________________
b You have 59 jubes to add to party bags. Each bag gets 5 jubes. How many full party bags
can you make?
SERIES TOPIC
Written methods – short division with remainders
4 One way is to write r 2 as in the example above. We use this when we don’t care about being absolutely
precise and when the remainder can’t be easily broken up. An example would be sharing 527 jelly beans
among 5 people. Solve these problems expressing the remainders as r.
a Share 126 blue pencils among 4 people. b Share 215 paper clips among 7 people.
4 1 2 0 0 2 2 7 0 0
We regularly come across multiplication and division problems in our everyday life. It doesn’t
matter which strategy we use to solve them, we can choose the one that suits us or the problem best.
1 One real-life problem is comparing prices to find the best deal. It’s easy if the prices and amounts are the
same but what if the amounts are different? Use a strategy to help you find the best deal on these:
a b
100 g 300 g
c d
10 pack CD Single CD
500 ml 2 litres
2 You go to the service station with your weekly pocket money of $5. When you take a $1.75 chocolate bar
to the counter, they offer you the special of 3 bars for $4.50. Which is a better deal? Show why.
SERIES TOPIC
Written methods – solving problems
3 You’re planning a trip to the Wet and Wild theme park and
there are many ticket options. Use a strategy of your choice
and the price list below to answer the following questions:
Entry Extras
b How much cheaper is this option than buying two 1-day passes?
c If you bought an annual pass, how many times would you need to visit to make it
a better option than buying either a 1-day or 2-day pass?
d What if you choose just the rides? How much would you save if you bought the
10-ride pass instead of the individual rides?
e If you took a 5-minute helicopter ride, what would be the cost per minute?
f What about if you chose the 10-minute flight option? What would be the cost per minute?
g Plan a day’s itinerary for you and a partner. How much will this cost?
What
to do Use the code below to work out the hidden message.
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __
2 1 3 6 4 5 3 8 7 9 8 9 10 12 11
T – M = A T is ______ 2 × L = I I = ______
T + T = H H is ______ (2 × L) – A = C C = ______
H – M = L L is ______ F + A = N N = ______
3 × L = U U is ______ 3 × T = S S = ______
What
to do Try this one:
__ __ __ __ __ __ __ __ __ __ __ __ __
2 9 4 12 13 8 2 7 4 9 2 12 3
__ __ __ __ __ __ __ __ __ __ __ __ __
4 2 6 6 3 12 0 8 9 1 2 5 3
A × A = A + A A is ______ L + E = S S is ______
A + A = T T is ______ N – N = I I is ______
If two letters
are together, T × 2 = N N is ______ U – A = C C is ______
we read
them as a AT ÷ N = E E is ______ S – (2 × T) = P P is ______
tens digit and
a units digit. 2 × E = L L is ______ 2 × U – P = O O is ______
E + T = U U is ______ S + E = R R is ______
SERIES TOPIC
Smart buttons apply
Getting In this activity, you’ll use your knowledge of multiplication, division, subtraction and
ready
addition to find as many number statements you can to create one number.
Choose another number to make and see how many statements you can find or
What challenge a partner to a competition. Set a time limit and see who can find the most
to do
ways to make 15 within the time span.
Bugs investigate
Getting
ready Use your knowledge of multiples to help you work out how many boy bugs and
girl bugs there are in the problem below. Listing all the multiples is a strategy that
would help.
What Girl bugs have 4 splodges on their backs, boy bugs have 9.
to do
Altogether there are 48 splodges. Work out how many girl
bugs and how many boy bugs there are.
What to
do next What if girl bugs have 8 splodges and boy bugs have 6 and there are 120 splodges
altogether? How many different answers can you find?
What Use your knowledge of multiplication to work out the missing values:
to do
a 2 8 b 7 c 7
× 3 × 4 × 5
8 2 8 8 2 3 5
d 8 e 6 8 f 2 3
× 9 × ×
7 2 9 2 0 4 6 5 8 4
g 2 6 1 h 4 2 i 5 6
× × 3 × 2 7
4 4 1 2 6 3 9 2
6 8 0
What
to do
Fill in the multiplication and division tables by × 3
working out the missing digits. The arrows show
you some good starting places. 4 32
14
45 27
× 7 6 × 8 9
12 24
20 16 14 12 24
5 40 3 12 × 9
36 14 6
3 30 54 11 33 44
63
8 64
SERIES TOPIC
Puzzles apply
8
7 7 × 3 6 12 × 12
9 9 × 6 8 39 ÷ 3
9 10
10 6 × 50
What
to do Test your speed and accuracy. Race against a partner or the clock to complete each table:
÷8 ÷3 ÷7
56 9 21
16 6 7
64 18 14
80 12 70
32 24 49
72 30 28
24 27 42
8 33 35