Lesson 13 Decompose Tens or Hundreds

    • Let’s decompose a ten or hundred to subtract.

Warm-up Which One Doesn’t Belong: Blocks and Blocks

Which one doesn’t belong?

  1. Base ten diagram. 10 tens with arrow pointing to 1 hundred.
  2. Base ten diagram. 1 hundred decomposed into 10 tens.
  3. Base ten diagram. 1 hundred with arrow pointing to 10 ones.
  4. Base ten diagram. 1 ten decomposed into 10 ones.

Activity 1 Subtract With Base-ten Diagrams

Mai used base-ten blocks to find the value of . Then, she started making a diagram to show her work.

Explain what Mai did in Step 2. Show what Mai should do next to find the difference.

Step 1

Base ten diagram. 3 hundreds, 3 tens, 6 ones.

Step 2

Base ten diagram. 3 hundreds, 3 tens, 6 ones. 1 hundred decomposed into 10 tens.

Write the matching expression for each diagram.  Then find the value of each difference.

  1. Base ten diagram. 2 hundreds, 4 tens, 4 ones. 1 hundred crossed out to show decomposition into 10 tens. 6 tens and 4 ones crossed out.
  2. Base ten diagram. 2 hundreds, 4 tens with 3 crossed out, 4 ones. Arrow from tens to 10 ones, 8 crossed out.
  3. Base ten diagram. 2 hundreds, one crossed out with arrow to 10 tens, 6 crossed out. 5 other tens. 6 ones, 4 crossed out.

Activity 2 Decompose a Ten or Hundred

Problem 1

Students drawing base ten diagrams.

Find the value of each difference. Show your thinking. Try Mai’s way for one expression.

Problem 2

Share how you found the value of one of the expressions to your partner. Use the sentence frames to help explain:

  • “First, I …”

  • “Next, I …”

  • “Then, I …”

  • “Last , I …”

Practice Problem

Problem 1

Find the value of each difference. Show your thinking.