Transcript Factors

Multiples and
Factors
Multiples
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A multiple is a number that is in the
times tables.
Multiples of 6 are
6, 12, 18, 24, 30…
Multiples of 20 are
20, 40, 60, 80, 100…
What are the multiples of…
4
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4, 8, 12, 16, 20…
9
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9, 18, 27, 36, 45…
30
 30, 60, 90, 120, 150…
Factors
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A factor is a number that divides
exactly into another number.
Factors of 6 are
1, 2, 3 and 6
Factors of 20 are
1, 2, 4, 5, 10 and 20
What are the factors of…
15
 1, 3, 5, 15
28
 1, 2, 4, 7, 14, 28
50
 1, 2, 5, 10, 20, 25, 50
Factor exploration
Start with any number:
 Write down all its
factors:
 Add all but the largest:
 Write down the factors
of the new number:
 Add all but the largest:
… and so on …
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9
 1, 3, 9
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1+3 = 4
 1, 2, 4
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1+2 = 3
 1, 3
 =1
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9431
This is called the factor chain for 9.
Draw factor chains for these
numbers:
(a) 16 (b) 29 (c) 12 (d) 6
(e) a number of your choice
(f) Challenge: 102 (this is long!)
Play “Juniper Green”
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A game for 2 players, played on a grid
like this:
1
2
3
4
5
6
7
8
9
10
11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30
31 32 33 34 35 36 37 38 39 40
Play “Juniper Green”
The first player puts a counter on an
even number.
 After that, players take turns,
putting a counter on either a factor
or a multiple of the last number
covered.
 The first player who is unable to
cover a number loses.
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Play “Juniper Green”
Show that this is a first player game
by finding the winning strategy for
the first player.
 Try playing on different sized grids.
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Juniper Green is named after the school where it was invented.
Thanks!
JRElse 2004