1. Multiplication with Arrays and Boxes – A Visual Model

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

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

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

5. 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

6. How do you solve 26 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. 26 49 20 6 409 20 x 40 = 800 6 x 40 = 240 20x9=180 6x9=54 Find the product of each new “imaginary” array. (These are much easier problems)

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

10. 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