Whole Number Subtraction
AZ Math Standards Performance Objectives (samples):
Strand 1: Number Sense and Operation
Concept 2: Numerical Operations
 Grade K PO2: Model subtraction with minuends of 10 using manipulatives.
 Grade 1 PO2: Demonstrate the process of subtraction with minuends of 20
using manipulatives.
 Grade 2 PO2: Demonstrate the process of subtraction using manipulatives with
two-digit whole numbers.
 Grade 3 PO2: Demonstrate the process of subtraction using manipulatives
through three-digit whole numbers.
Take Away Approach
 For this approach we are considering a question such as the following: Elizabeth
has 7 cookies in her lunch bag. She ate three of these cookies on the way to
school. How many cookies will she have left for lunch?

Set Model for 7 – 3 = 4
      

Base Ten Block Model for 76 – 23 = 53
Comparison Approach
 For this approach we are considering a question such as the following: Elizabeth
has 7 cookies in her lunch bag. Jason has 3 cookies in his lunch bag. How many
more cookies does Elizabeth have?

Set Model for 7 – 3 = 4
      
  
Whole Number Subtraction 1

Base Ten Block Model for 76 – 23 = 53
Missing Addend / Counting On Approach
 For this approach we are considering a question such as the following: Elizabeth
would like to have 7 dollars to buy a special toy. She already has 3 dollars. How
many more dollars does she need?

Set Model
      

Base Ten Block Model for 76 – 23 = 53
Whole Number Subtraction 2
Subtraction of Whole Numbers: Models and Algorithms
1. Find the following differences using the base ten pieces for the Take Away, Comparison
and Missing Addend approaches. Include a drawing of your model.
9
59
4
 14
2. Find the following differences using the base ten pieces for the Take Away, Comparison
and Missing Addend approaches. Include a drawing of your model.
17
32
 8
 18
Whole Number Subtraction 3
3. You are probably familiar with the term borrow to describe part of the subtraction
algorithm. Explain how regrouping more accurately describes this process than
the word borrow.
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4. Write a word problem for 19 – 5 = 14 using the Take Away Approach.
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5. Write a word problem for 19 – 5 = 14 using the Comparison Approach.
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6. Write a word problem for 19 – 5 = 14 using the Missing Addend Approach.
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Whole Number Subtraction 4