1. Multiplication with Arrays and Boxes

2. How do you solve 17x34 using an array?

3. The goal is to make easier problems that can be solved without a calculator.34 17

4. Split the array at the place value
Split the array at the place value. For example, 17 is split into 10 and 7.
Find the product of each new array.
(These are much easier problems) 34 4 30
10x4=40
10 x 30 = 300 10 17 7
7x4=28
7 x 30 = 210

5. Finally, add up the products.
300
210 40
+28
10x4=40
10 x 30 = 300
578
7x4=28
7 x 30 = 210
17 x 34 = 578

6. How do you solve 26 x 49 using a box
How do you solve x 49 using a box? (that would be too many dots to draw)

7. First, draw a rectangular box. Treat this box like a 26 x 49 array.

8. 26 rows, 49 in each row. Split those numbers at the place value.
Find the product of each new “imaginary”
array. (These are much easier problems) 40 49 9
20x9=180
20 x 40 = 800 26 20 6
6x9=54
6 x 40 = 240

9. Finally, add up the products just like you did with the array.
800
240
180
+54
20x9= 180
20 x 40 = 800
1,274
6x9= 54
6 x 40 = 240
26 x 49 = 1,274

10. Try these problems for practice
Try these problems for practice. If you need help, look back at the previous slides.
17 x 25
28 x 31
39 x 23
47 x 72
56 x 17
49 x 85
99 x 99