Transcript Multiplication with Arrays and Boxes

Multiplication with Arrays and
Boxes – A Visual Model
How do you solve 17x34 using an array?
The goal is to make easier problems
that can be solved without a calculator.
34
17
Split the array at the place value. For example, 17 and 34
are split into 10 and 7 and 30 and 4.
30
10
34
4
10 x 30 = 300
10x4=40
7 x 30 = 210
7x4=28
17
7
Find the product of each new array.
(These are much easier problems)
Finally, add up the products.
10 x 30 = 300
7 x 30 = 210
10x4=40
7x4=28
300
210
40
+28
578
17 x 34 = 578
How do you solve
26 x 49 using a box?
(that would be too many dots to draw)
First, draw a rectangular box. Treat
this box like a 26 x 49 array.
26 rows, 49 in each row. Split those numbers at
the place value.
49
40
9
20
20 x 40 = 800
20x9=180
6
6 x 40 = 240
6x9=54
26
Find the product of each new “imaginary”
array. (These are much easier problems)
Finally, add up the products just like you
did with the array.
800
240
20 x 40 = 800 180
20x9= 180
+54
6 x 40 = 240 1,274
6x9= 54
26 x 49 = 1,274
Try these problems for practice. If you
need help, look back at the previous slides.
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17 x 25
28 x 31
39 x 23
47 x 72
56 x 17
49 x 85
99 x 99