Multiply Using Partial Products micro-lesson

Chris Lindsey

Maths

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When you multiply two digits by two digits, you might want to try the partial product method. Let's take 85 x 29. We’ll first look at this 9 in the ones place. We're going to multiply it twice, 9 x 5 is 45 and 9 x 80 is 720. Now, if I look at the 2, and I realize the two is in the tens place so it's worth 20. So, I'm going to multiply by 20, 20 x 5 is 100 and 20 x 80 is 1,600. Our final step is to add up all of the partial products 45 + 720 + 120 and 1,600 gives us 2,465 for our final product of 85 x 29. The partial product strategy is another great method for multiplying two digits by two digits.

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How much is the 2 worth in the problem 85 x 29?

1) 20

2) 2

3) 200

4) 2000
How many partial products will you have for 85 x 29?

1) 4

2) 3

3) 2

4) 1
How many partial products will you have for 27 x 48?

1) 4

2) 3

3) 2

4) 1
How many partial products will 95 x 3 have?

1) 2

2) 3

3) 4

4) 5
How many partial products will 56 x 7 have?

1) 2

2) 3

3) 4

4) 5
Use two partial products to solve 56 x 7.

1) 392

2) 77

3) 239

4) 342
How much is the 9 worth in the problem 85 x 29?

1) 9

2) 90

3) 900

4) 9000
Use the partial product method to solve 84 x 2.

1) 168

2) 160

3) 640

4) 174
The partial products for 25 x 13 are 200, 60, 50, and 15. What is the final product?

1) 325

2) 265

3) 310

4) 350
Use the partial product method to solve 65 x 7.

1) 455

2) 420

3) 95

4) 425
Use the partial product strategy to solve 39 x 15.

1) 585

2) 485

3) 72

4) 288
What is the final product for 85 x 29?

1) 2465

2) 2546

3) 2645

4) 2564
Use the partial product method to solve 91 x 43.

1) 3913

2) 3600

3) 3870

4) 4050
Use the partial product strategy to solve 82 x 63.

1) 5166

2) 4800

3) 5009

4) 5100
A farmer has 57 cows. Each cow produces 28 liters of milk. How many liters of milk do the cows produce in all?

1) 1,596 liters of milk

2) 210 liters of milk

3) 696 liters of milk

4) 120 liters of milk
What are the partial products for 95 x 3?

1) 270 + 15

2) 27 + 15

3) 270 + 150

4) 2,700 + 15
Which of these shows the correct partial products for this problem?

1) 3,600 + 40 + 270 + 3

2) 30 + 40 + 27 + 360

3) 30 + 270 + 4 + 3,600

4) 3,600 + 40 + 27 + 30
What are the four partial products you should add together to find the total product for this problem?

1) Any of the above will work.

2) 6 + 240 +120 + 4,800

3) 240 + 120 + 4,800 + 6

4) 4,800 +120 + 6 + 240
Emma says the partial products for 84 x 2 are 8 and 16. What did she do wrong?

1) She multiplied 2 x 8 instead of 2 x 80.

2) She added 2 + 80 instead of multiplying 2 x 80.

3) She multiplied 2 x 8 instead of adding 2 + 8.

4) She added 2 + 4 instead of multiplying 4 x 2.
Lola says the partial productsmay be added in any order. Is she correct?

1) Yes

2) No
Brad says the partial products for 57 x 31 are 7, 50, 210, and 1,500. Is he correct?

1) Yes

2) No
Elsa says the partial products for 23 x 92 are 6, 4, 27, and 18. Is she correct?

1) No

2) Yes
It is critical to line up your place values as your write down your partial products/

1) TRUE

2) FALSE
The 6 in 65 x 7 is worth 60.

1) TRUE

2) FALSE

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Chris Lindsey

Elementary Teacher in South Carolina, USA. I have been teaching 4th and 5th grades for the past 11 years. My passion is teaching Math, but my love is reading aloud to children.

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