Lesson 12 Add Tens to Two-digit Numbers

    • Let’s add tens to two-digit numbers.

Warm-up True or False: Tens and Ones

Decide if each statement is true or false.
Be prepared to explain your reasoning.

Activity 1 Add Two-digit Numbers and Tens

Students thinking

Find the number that makes each equation true.
Show your thinking using drawings, numbers, or words.

Activity 2 The Missing Digit

  1. This equation is true.

    Equation with missing tens digit. 56, plus, smudge covering the tens digit, 0 ones, equals 96.

    What digit is under the smudge?
    Show your thinking using drawings, numbers, or words.

  2. This equation is not true.

    Equation with missing tens digit. Smudged tens digit, 3 ones, plus 30, equals 74.

    Show why it is not true using drawings, numbers, or words.

Practice Problem

Problem 1

Find the number that makes each equation true.
Show your thinking using drawings, numbers, or words.