Lesson 14 Ways to Represent Multiplication of Teen Numbers

    • Let’s make sense of some ways to represent the multiplication of teen numbers.

Warm-up Notice and Wonder: Seeing Groups

What do you notice? What do you wonder?

2 groups of 12 squares.
Base ten blocks. 2 groups of 1 ten and 2 ones.
Base ten blocks. 2 sets of 1 ten and 2 ones.

Activity 1 A Factor Greater than Ten

Tyler says he can use base-ten blocks to find the value of because he knows and . He says this diagram proves his thinking.

Base ten blocks. 7 sets of 1 ten and 3 ones.

  1. Do you agree or disagree? Explain your reasoning.

  2. Use Tyler’s method to find the value of  . Explain or show your reasoning.

Activity 2 Ways to Represent

Andre, Clare, and Diego represented the same expression. Their representations are shown below.

Andre
Area diagram. Rectangle divided into 2 parts.
Diego
Area diagram.
Clare
Base ten blocks.

  1. Where do you see the factors in each diagram?

  2. Where do you see the product in each diagram?

Practice Problem

Problem 1

  1. What do the 60 and 24 in the diagram represent?

    Area diagram. Rectangle divided into 2 parts. One part labeled 60 with a top measurement of 10, the other labeled 24, with a top measurement of 4. Left side measurement 6.

  2. Explain how to use the diagram to calculate .