Math Module 3 Multi-Digit Multiplication and Division Topic B: Multiplication by 10, 100, and 1,000 Lesson 6: Multiply two-digit multiples of 10 by two-digit multiples of 10 with the area model 4.OA.1 4.OA.2 4.NBT.5 4.NBT.1

I can multiply! Lesson 6 Target You will multiply two digit multiples of 10 by two-digit multiples of 10

(Write 3 × 2 = .) Say the multiplication sentence in unit form. S: 3 ones × 2 = 6 ones. T: Write the answer in standard form. S: (Write 6.) T: (Write 30 × 2 = .) Say the multiplication sentence in unit form. S: 3 tens × 2 = 6 tens. S: (Write 60.) Fluency Multiply Units Lesson 6 3 x 2 = ____ Say the multiplication sentence in unit form. 3 ones × 2 = 6 ones. Write the answer in standard form. Did you write 6? 30 x 2 = ____ Say the multiplication sentence in unit form. 3 tens × 2 = 6 tens. Write the answer in standard form. Did you write 60?

(Write 3 × 2 = .) Say the multiplication sentence in unit form. S: 3 ones × 2 = 6 ones. T: Write the answer in standard form. S: (Write 6.) T: (Write 30 × 2 = .) Say the multiplication sentence in unit form. S: 3 tens × 2 = 6 tens. S: (Write 60.) Fluency Multiply Units Lesson 5 300 x 2 = ____ Say the multiplication sentence in unit form. 3 hundreds × 2 = 6 hundreds. Write the answer in standard form. Did you write 600? 3,000 x 2 = ____ Say the multiplication sentence in unit form. 3 thousands × 2 = 6 thousands. Write the answer in standard form. Did you write 6,000?

(Write 3 × 2 = .) Say the multiplication sentence in unit form. S: 3 ones × 2 = 6 ones. T: Write the answer in standard form. S: (Write 6.) T: (Write 30 × 2 = .) Say the multiplication sentence in unit form. S: 3 tens × 2 = 6 tens. S: (Write 60.) Fluency Multiply Units Lesson 5 3,000 x 3 = ____ Say the multiplication sentence in unit form. 3 thousands × 3 = 9 thousands. Write the answer in standard form. Did you write 9,000? 30 x 3 = ____ Say the multiplication sentence in unit form. 3 tens × 3 = 9 tens. Write the answer in standard form. Did you write 90?

(Write 3 × 2 = .) Say the multiplication sentence in unit form. S: 3 ones × 2 = 6 ones. T: Write the answer in standard form. S: (Write 6.) T: (Write 30 × 2 = .) Say the multiplication sentence in unit form. S: 3 tens × 2 = 6 tens. S: (Write 60.) Fluency Multiply Units Lesson 6 300 x 5 = ____ Say the multiplication sentence in unit form. 3 hundreds × 5 = 15 hundreds. Write the answer in standard form. Did you write 1,500? 70 x 5 = ____ Say the multiplication sentence in unit form. 7 tens × 5 = 35 tens. Write the answer in standard form. Did you write 350?

(Write 3 × 2 = .) Say the multiplication sentence in unit form. S: 3 ones × 2 = 6 ones. T: Write the answer in standard form. S: (Write 6.) T: (Write 30 × 2 = .) Say the multiplication sentence in unit form. S: 3 tens × 2 = 6 tens. S: (Write 60.) Fluency Multiply Units Lesson 5 400 x 8 = ____ Say the multiplication sentence in unit form. 4 hundreds × 8 = 32 hundreds. Write the answer in standard form. Did you write 3,200? 7,000 x 2 = ____ Say the multiplication sentence in unit form. 7 thousands × 2 = 14 thousands. Write the answer in standard form. Did you write 14,000?

(Write 3 × 2 = .) Say the multiplication sentence in unit form. S: 3 ones × 2 = 6 ones. T: Write the answer in standard form. S: (Write 6.) T: (Write 30 × 2 = .) Say the multiplication sentence in unit form. S: 3 tens × 2 = 6 tens. S: (Write 60.) Fluency Multiply Units Lesson 6 800 x 5 = ____ Say the multiplication sentence in unit form. 8 hundreds × 5 = 40 hundreds. Write the answer in standard form. Did you write 4,000? 40 x 5 = ____ Say the multiplication sentence in unit form. 4 tens × 5 = 20 tens. Write the answer in standard form. Did you write 200?

20 Take Out the 10, 100, or 1,000 Fluency Lesson 6 Lesson 6 I’ll say a number. I want you to restate the number as a multiplication sentence, taking out the 10, 100,or 1,000. Ready? 90 200 20 2,000 30 5,000 700 8,000 8 x 1,000 5 x 1,000 2 x 1,000 2 x 10 2 x 100 9 x 10 3 x 10 7 x 100

Multiply by Multiples of 10, 100, and 1,000 Lesson 6 Say the multiplication problem. Fluency Multiply by Multiples of 10, 100, and 1,000 Lesson 6 5 x 300 Rewrite the problem the multiplication sentence taking out the 100 and solve. Did you write 5 x 3 x 100 = 1,500

Multiply by Multiples of 10, 100, and 1,000 Lesson 6 Say the multiplication problem. Fluency Multiply by Multiples of 10, 100, and 1,000 Lesson 6 70 x 3 Rewrite the problem the multiplication sentence taking out the 10 and solve. Did you write 7 x 3 x 10 = 210

Multiply by Multiples of 10, 100, and 1,000 Lesson 6 Say the multiplication problem. Fluency Multiply by Multiples of 10, 100, and 1,000 Lesson 6 8 x 4,000 Rewrite the problem the multiplication sentence taking out the 1,000 and solve. Did you write 8 x 4 x 1,000 = 32,000

Multiply by Multiples of 10, 100, and 1,000 Lesson 6 Say the multiplication problem. Fluency Multiply by Multiples of 10, 100, and 1,000 Lesson 6 6 x 200 Rewrite the problem the multiplication sentence taking out the 100 and solve. Did you write 6 x 2 x 100 = 1,200

Multiply by Multiples of 10, 100, and 1,000 Lesson 6 Say the multiplication problem. Fluency Multiply by Multiples of 10, 100, and 1,000 Lesson 6 50 x 8 Rewrite the problem the multiplication sentence taking out the 10 and solve. Did you write 5 x 8 x 10 = 400

Read! Draw! Write! RDW Review Can you draw something?  What can you draw?  What conclusions can you make from your drawing? Lesson 6 RDW Review Read! Draw! Write!

Application Problem Lesson 6 Lesson 6 There are 400 children at Park Elementary School. Park High School has 4 times as many students. How many students in all attend both schools? Lane High School has 5 times as many students as Park Elementary. How many more students attend Lane High School than Park High School?

Concept Development Problem 1: Use the place value chart to multiply a two-digit multiple of 10 by a two-digit multiple of 10. Lesson 6 30 x 20 Here we are multiplying a two-digit number by another two-digit number. What are some other ways we could express 30 × 20? 3 tens × 2 tens. 10 × 20 × 3. 10 × 30 × 2. 2 × 30 × 10. 3 × 20 × 10. Let’s use 10 × 20 × 3 in a place value chart to help us solve 30 × 20. What is 2 tens times 10? 2 tens times 10 is 2 hundreds. So the value of 10 × 20 is? 200. And then 200 × 3? You could triple the group or multiply by units. 10 × 20 × 3 is?

Did you get the same answer? With your partner, represent one of the following on your place value chart: 10 × 30 × 2 as 10 groups of 30 times 2 2 × 30 × 10 as 2 groups of 30 times 10 3 × 20 × 10 as 3 groups of 20 times 10 When we multiply a two-digit number by another two-digit number, there are many equivalent ways to express it as a product. Decomposing our multiplication problem into more units can help us solve. Concept Development Problem 1 Lesson 6 With your partner, represent one of the following on your place value chart: 2 × 30 × 10 as 2 groups of 30 times 10 10 × 30 × 2 as 10 groups of 30 times 2 3 × 20 × 10 as 3 groups of 20 times 10

Concept Development Problem 2: Create an area model to represent a two-digit multiple of 10 by two-digit multiple of 10. Lesson 6 40 x 20 Let’s model 40 × 20 as an area. Tell your partner what 40 × 20 is. 4 tens times 20. That’s 80 tens or 800. What is 20 in unit form? 2 tens is correct. So then, what is 4 tens times 2 tens? You know 4 times 2 is 8. That leaves both tens. 10 tens. It’s like saying 4 times 2 times 10 tens! Let’s prove how we can multiply the units.

Concept Development Problem 2: Create an area model to represent a two-digit multiple of 10 by two-digit multiple of 10. Lesson 6 You drew a 40 by 20 rectangle. Now partition the horizontal side into 2 tens and the vertical side into 4 tens. Label each side. What is the area of the square? 10 times 10 is 100. Say a multiplication sentence for how many of the squares there are. 2 times 4 equals 8. Tell your partner how this rectangle shows 4 tens times 2 tens equals 8 hundreds. Each square is 10 by 10. That makes 100. There are 8 hundreds.

50 x 40 Concept Development Name 50 × 40 in unit form. Problem 3: Use an area model to represent a two-digit multiple of 10 by a two-digit multiple of 10. Lesson 6 50 x 40 Name 50 × 40 in unit form. 5 tens times 4 tens. With your partner, draw a rectangle to represent 5 tens times 4 tens. You can draw the vertical side as 5 tens and the horizontal side as 4 tens. 10 times 10 is 100. 5 times 4 is 20. 20 is the same as 2 tens. 2 tens times 100 is 2,000.

Use a place value chart to prove 2 tens times 100 is 2,000. Concept Development Problem 3: Use an area model to represent a two-digit multiple of 10 by a two-digit multiple of 10. Use a place value chart to prove 2 tens times 100 is 2,000. Lesson 6 50 x 40 Use a place value chart to prove 2 tens times 100 is 2,000.

50 x 40 Concept Development What is 50 × 40? 50 times 40 is 2,000. Problem 3: Use an area model to represent a two-digit multiple of 10 by a two-digit multiple of 10. Use a place value chart to prove 2 tens times 100 is 2,000. Lesson 6 50 x 40 What is 50 × 40? 50 times 40 is 2,000. What conclusion can be made about multiplying a unit of 10 times a unit of 10? 10 times 10 is always 100. So I can decompose any unit of 10, multiply how many units of 10 there are, and it will be that many hundreds. 7 tens times 8 tens is 56 of some unit. I just have to find the unit. Ten times ten is 100. So it’s 56 hundreds or 5,600.

60 x 30 Your turn! Try it with 60 x 30! Concept Development Problem 3: Use an area model to represent a two-digit multiple of 10 by a two-digit multiple of 10. Lesson 6 Your turn! Try it with 60 x 30! 60 x 30 Name 60 × 30 in unit form. 6 tens times 3 tens. With your partner, draw a rectangle to represent 6 tens times 3 tens. You can draw the vertical side as 3 tens and the horizontal side as 6 tens. 10 times 10 is 100. 6 times 3 is 18. 18 is the same as 1 ten 8 ones. 1 ten times 100 is 1,000. 8 ones time 100 is 800. 1,000 and 800 is 1,800.

60 x 30 Concept Development What is 60 × 30? 60 times 30 is 1,800. Use a place value chart to prove 2 tens times 100 is 2,000. Concept Development Problem 3: Use an area model to represent a two-digit multiple of 10 by a two-digit multiple of 10. Lesson 6 60 x 30 30 What is 60 × 30? 60 times 30 is 1,800. What conclusion can be made about multiplying a unit of 10 times a unit of 10? 10 times 10 is always 100. So I can decompose any unit of 10, multiply how many units of 10 there are, and it will be that many hundreds. 6 tens times 3 tens is 18 of some unit. I just have to find the unit. Ten times ten is 100. So it’s 18 hundreds or 1,800. 60 x 30 6 tens x 3 tens 18 hundreds 1,800 60

Problem Set 10 Minutes Lesson 6

What patterns did you notice while solving Problem Set 10 Minutes Lesson 6 Talk to your partner about how you each solved Problem 2. Can you come up with a different way to solve this problem? What patterns did you notice while solving Problem 1?

Problem Set 10 Minutes Lesson 6

Problem Set 10 Minutes Lesson 6

Problem Set 10 Minutes Lesson 6

Problem Set 10 Minutes Explain to your partner how to solve the problem 80 × 50 from Problem 10. What does the answer have to do with thousands when the units in 80 and 50 are 8 tens and 5 tens? Lesson 6

Debrief To solve 4 × 10 × 2 × 10, you can multiply 4 × 2 to get 8, then multiply 10 × 10 to get 100, then multiply the 8 times 100. Is it always possible to rearrange numbers like this when multiplying? Lesson Objective: Multiply two-digit multiples of 10 by two-digit multiples of 10 with the area model.

Exit Ticket Lesson 4

There are three pages of homework tonight…