Multi-Digit Multiplication

Lesson 7

Math

Unit 2

4th Grade

Lesson 7 of 18

Objective


Multiply two-digit numbers by one-digit numbers.

Common Core Standards


Core Standards

  • 4.NBT.B.5 — Multiply a whole number of up to four digits by a one-digit whole number, and multiply two two-digit numbers, using strategies based on place value and the properties of operations. Illustrate and explain the calculation by using equations, rectangular arrays, and/or area models.

Foundational Standards

  • 3.NBT.A.3
  • 4.NBT.A.1
  • 4.NBT.A.2
  • 4.NBT.B.4
  • 3.OA.B.5
  • 3.OA.C.7

Criteria for Success


  1. Understand that products can be computed by decomposing numbers into base-ten units, finding partial products of these base-ten units and the multiplier, then adding these partial products together based on the distributive property (e.g., $$365\times4=(300\times4)+(60\times4)+(5\times4)$$). (Note that students need not know the term “distributive property.”)
  2. Multiply a two-digit whole number by a one-digit whole number using area models and equations. 
  3. Estimate products by rounding factors to the largest place value.
  4. Solve one-step word problems involving multiplication of two-digit by one-digit numbers, understanding that an area model can be used to solve equal groups and comparison problems (MP.4).

Tips for Teachers


  • Throughout the remainder of the topic, the main visual model used is the area model. If students seem to be struggling with place value understanding or don’t yet seem ready for the area model for some other reason, you might create a lesson to use before this one that focuses on the use of the base ten block array and/or graph paper array to build understanding toward the area model. This applet Partial Product Finder by the Math Learning Center may be helpful if you take that route. (See Unit-Specific Intellectual Prep section of the Unit Overview for examples of those representations.)
  • Before or in place of much of the purely computational tasks on the Problem Set, you could have students play the game “Multiplication Mix-Up” from Building Conceptual Understanding and Fluency Through Games (Grade 5) by the North Carolina Department of Public Instruction.
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Anchor Tasks


Problem 1

Mr. Wynn gets some butcher paper from the teacher supply room to put down the length of the hallway. The butcher paper is 3 feet tall and 30 feet long. When he puts it up in the hallway, he realizes he needs a little more to fully cover the wall. The extra piece he needed is 3 feet tall and 2 feet long. 

a.   How many square feet of butcher paper did Mr. Wynn put in the hallway? 

b.   What was the total length of width of the space Mr. Wynn ended up covering? 

Guiding Questions

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References

EngageNY Mathematics Grade 4 Mathematics > Module 3 > Topic C > Lesson 8Concept Development

Grade 4 Mathematics > Module 3 > Topic C > Lesson 8 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..

Modified by Fishtank Learning, Inc.

Problem 2

a.   Estimate the product 57 $$\times$$ 9. 

b.   The area model below represents 57 $$\times$$ 9. 

  1. Label each region of the area model with its respective area. 
  2. Find the value of 57 $$\times$$ 9. Show your reasoning.

Guiding Questions

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Problem 3

a.   Solve each of the following word problems. Show or explain your work. 

  1. In the 2017–2018 school year, Match Community Day had 61 students in each grade level. How many students were at Match Community Day that year if the school had Kindergarten and Grades 1–4? 
  2. A club’s first meeting was attended by 28 people. The second meeting was attended by 4 times as many people as the first meeting. How many people attended the second meeting? 

b.   Did you use an area model to represent either or both problems in Part (a)? If not, could you have? Why or why not? 

Guiding Questions

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References

EngageNY New York State Testing Program Grade 4 Common Core Mathematics Test Released Questions with Annotations August 2013page 9

From EngageNY.org of the New York State Education Department. New York State Testing Program Grade 4 Common Core Mathematics Test Released Questions with Annotations August 2013. Internet. Available from https://www.engageny.org/resource/new-york-state-common-core-sample-questions/file/103191; accessed March 23, 2018, 3:44 p.m..

Modified by Fishtank Learning, Inc.

Problem Set


Answer Keys

Unlock the answer keys for this lesson's problem set and extra practice problems to save time and support student learning.

Discussion of Problem Set

  • Look at #2. Was anyone's estimate very far from their actual product? What did you do when you noticed that mismatch? 
  • The model used in #3 is different from the ones we’ve seen so far. How is it similar to and different from an area model? Which answers were you able to eliminate right away? 
  • Can you use an area model for #4–#6? Why or why not? 
  • Did you use any strategies from Lesson 6 to solve any problems on today’s Problem Set? For example, #7c or #7d? 

Target Task


Problem 1

In the area model shown, what are the values of A and B?

Problem 2

Solve. Show or explain your work.

35 $$\times $$ 7

Problem 3

A countertop in a kitchen measures 4 feet deep by 26 feet long. What is the area, in square feet, of the countertop?

Student Response

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Additional Practice


The Extra Practice Problems can be used as additional practice for homework, during an intervention block, etc. Daily Word Problems and Fluency Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Extra Practice Problems

Answer Keys

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Word Problems and Fluency Activities

Word Problems and Fluency Activities

Help students strengthen their application and fluency skills with daily word problem practice and content-aligned fluency activities.

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Lesson 6

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Lesson 8

Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Multiplicative Comparison

Topic B: Multiplication of up to Four-Digit Whole Numbers by One-Digit Whole Numbers

Topic C: Multiplication of Two-Digit Whole Numbers by Two-Digit Whole Numbers

Topic D: Multi-Step Word Problems

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