Curriculum  /  Math  /  4th Grade  /  Unit 2: Multi-Digit Multiplication  /  Lesson 12

Multi-Digit Multiplication

Lesson 12

Math

Unit 2

4th Grade

Lesson 12 of 18

Objective

Multiply two-digit multiples of 10 by two-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.B.4
  • 3.OA.B.5
  • 3.OA.C.7

Criteria for Success

  1. Multiply multiples of 10 by two-digit numbers by decomposing the multiply of 10 and using the associative property (e.g., 80 × 34 = 8 × 10 × 34 = 272 × 10). (Note that students need not know the term “associative property.”)
  2. Multiply multiples of 10 by two-digit numbers by decomposing the two-digit number and using the distributive property (e.g., 80 × 34 = (80 × 30) + (80 × 4) = 2,400 + 320 = 2,720). (Note that students need not know the term “distributive property.”)
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Anchor Tasks

25-30 minutes

Problem 1

Two different students solved the problem 40 × 22 below. Explain what each student did and whether the strategy they used works. 

Student A

Student B

Guiding Questions

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Student Response

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Problem 2

Estimate each product. Then use any method to find the product. 

a.   60 × 31

b.   18 × 70

c.   90 × 56

d.   35 × 80

Guiding Questions

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Student Response

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Problem Set

15-20 minutes

Discussion of Problem Set

  • How is #1a of the Problem Set less complex than the others?
  • How could you have used #3b to solve #4b? 
  • How could you have used #3c to solve #4c?
  • Can you explain why #4c and #4d have the same product?
  • When we record partial products, do we have to start with the one with the smallest place value? Will we get a different result if we start with the tens?
  • When one of the factors has a 0 in the ones place, why is there always a 0 in the ones place of the solution?

Target Task

5-10 minutes

Problem 1

Which of these expressions can be used to find the product $$20\times41$$? Select the two correct answers.

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Student Response

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Problem 2

Solve. Show or explain your work. 

$$32\times60$$

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.

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.

Next

Multiply two-digit numbers by two-digit numbers using a variety of mental strategies.

Lesson 13
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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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