Number Talks - Strategies for Multiplication
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Essential strategies and skills – building arrays, distributive property, partial products
Additional strategies – double and halving; decomposing factors; using multiples of 10, 100
Begin with multiplication strings to work on strategies. Sample strategies below.
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knowing twos using doubles,
knowing fours using double/doubles,
knowing three’s by adding a group to the two’s fact or subtracting a group from the three’s
group,
knowing seven’s as adding the group of 3 and group of 4 (this will help on adding), or knowing
fives and twos to make seven groups.
Knowing sixes – double of threes.
Knowing nines by multiplying by ten and subtracting a group
Knowing eights by doubling the 4 facts
Do the multiplication in this order, asking what strategy and patterns they see!
2x7
4x7
3x7
7x 7
2x5
4x5
3x5
7x5
2x4
4x4
3x4
7x4
2 x 10
4 x 10
3 x 10
7 x 10
2x3
4x3
3x3
7x3
Do both
columns
2x4
2x8
4x4
4x8
3x4
3x8
7x4
7x8
2x6
4x6
3x6
7x6
2x9
4x9
3x9
7x9
2x8
4x8
3x8
7x8
8x7
6x9
5x7
9x3
4x6
2x6x7x5
4 x 34 x 25
3x2x3x5
4x4x8x5
6x8x5x2
9 x 4 x 25
2 x 78 x 10
25 x 2 x 36
75 x 12
18 x 25 x 8
4 x 7 x 25 x 3
25 x 16 x 3
These set of problems can help with factoring and seeing patterns. 128 + 136 = 4(32+34)=8(16+17)
56 + 48
24 + 33
16 + 8
42 + 14
18 + 81
27 + 72
36 + 63
36 + 24
125 +
150 +
32 + 128
236 + 124
325
250
Once they are familiar with the strategies, move to two digits by one digit. You can do only one
problem, but this may be more challenging. Put up the first problem and get the answer, then have
them answer the second one. See if they start to use the addition or doubling in their head.
23 x 2
32 x 2
23 x 3
32 x 3
17 x 2
23 x 4
32 x 4
23 x 6
32 x 6
17 x 4
17 x 3
17 x 6
52 x 2
52 x 3
76 x 2
82 x 2
99 x 2
52 x 4
52 x 6
76 x 4
82 x 6
99 x 6
This strategy could
be 100 x 2 then
subtract 2. If they
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Number Talks - Strategies for Multiplication
do not come up
with it, then show
them this and see
what they would
do for 99x6
98 x 2
89 x 2
48 x 6
49 x 6
49 x 7
98 x 5
91 x 4
48 x 9
49 x 9
49 x 8
Throw these number talks in to work on multiples, or do them before the two digit numbers
7x5
8x5
6x5
5x5
5x5
7 x 10
8 x 10
6 x 10
5 x 10
5 x 10
7x9
8x9
6x9
5 x 20
5 x 30
5 x 19
5 x 29
2 x 20
4x5
6 x 20
36 x 3
36 x 6
2 x 19
4 x 49
6 x 19
36 x 30
36 x 30
45 x 3
45 x 6
82 x 3
82 x 6
12 x 13
45 x 30
45 x 60
82 x 30
82 x 60
71 x 4
71 x 8
29 x 4
29 x 8
16 x 23
71 x 40
71 x 80
29 x 40
29 x 80
8 x 12
8 x 24
8 x 32
8 x 82
8 x 99
8 x 106
8 x 115
8 x 120
8 x 250
8 x 405
5 x 26
5 x 63
5 x 27
5 x 82
5 x 99
5 x 115
5 x 118
5 x 126
5 x 184
5 x 208
12 x 5
12 x 6
12 x 8
12 x 9
12 x 13
12 x 15
12 x 35
12 x 25
15 x 24
25 x 16
32 x 15
28 x 15
16 x 15
45 x 12
16 x 45
During the fractions, work on simplifying fractions by factoring. Remember there is no canceling! Find
16
2𝑥8
8
32
2𝑥4𝑥4
1
the different representations of 1. Example – 46 = 2 𝑥 23 = 23; or 96 = 2 𝑥 4 𝑥 4 𝑥 3 = 3 The idea is that
we are multiplying or dividing by 1 to find another representation of the number. This uses the identity
property of multiplication. Work also on simplifying improper fraction.
16/46
8/48
32/56
10/16
17/32
32/96
18/36
15/35
9/81
8/86
88/4
36/6
39/6
28/12
15/4
32/9
62/7
121/11
18/5
72/18
Percents and fractions can be practiced daily
50% of 120
50% of 90
50% of 48
50% of 33
50% of 1000
Of 240
Of 180
Of 96
Of 66
of 100
Of 480
Of 360
Of 24
Of 99
Of 10
25% of 16
25% of 84
25% of 360
¼ x 16
Of 160
25% of 168
25% of 120
¼ x 160
Of 320
25% of 336
25% of 480
¼ x 320
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Number Talks - Strategies for Multiplication
Cathy Shide, Math Coach
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cathy.integrated@bluetie.com