Subtract Whole Numbers

Unit 2 Lesson 5

Objectives

• Explain and apply standard step-by-step approaches for subtraction.

• Use an inverse relationship to simplify a computation or check a result.

• Determine a missing number in an equation or an inequality.

• Determine the sum or difference of two whole numbers.

• Use the inverse relationship between addition and subtraction to solve problems.

Inverse operations are opposite operations because they undo each other.

Example:

15 + 8 = 23

23- 8 = 15

*Think about it: how are these two problems related?

Use the inverse operation to find the answer!

Use the inverse operation to find the answer!

Now, let’s look at 3 different ways to solve a subtraction problem!

Method 1: Addition to Subtract

5,523- 2,357

Begin with the lesser number and

add up to get to the greater number.

Lesser Number

Greater Number

Method 1: Addition to Subtract

5,523- 2,357

We’ll start with the ones place. Look at the lesser

number and see how many ones we need to add on.

2,357+3=2,360

Method 1: Addition to Subtract

5,523 -2,357

Next we’ll look at the tens place. We need

to figure out what to add to 2,360 to get to the next number in the hundreds place.

2,357+3=2,360 + 40 2,400

Target Number

Method 1: Addition to Subtract

5,523 -2,357

Now we’ll move to the hundreds place. I

need to figure out how many hundreds to add to get to the next thousand.

2,357+3=2,360 + 40 2,400 + 600 3,000

Target Number

Method 1: Addition to Subtract

5,523 -2,357

Then we’ll move to the thousands place. Our target number is 5,523, so I need to add 2,000 to get to 5,000.

2,357+3=2,360 + 40 2,400 + 600 3,000 +2,000 5,000

Target Number

Method 1: Addition to Subtract

5,523 -2,357

Next I need to add hundreds, tens and ones until I get to 5,523. I need to add 523 to 5,000.

2,357+3=2,360 + 40 2,400 + 600 3,000 +2,000 5,000 + 523 5,523

Target Number

Method 1: Addition to Subtract

Now I find the sums of everything I added to find how much I counted up.

2,357+3=2,360 + 40 2,400 + 600 3,000 +2,000 5,000 + 523 5,523

3 40 600 2,000+ 523

3,166

Method 2: Place Value

First, we need to look at the expanded form of the number with the least value.

2,000 + 300 + 50 + 7

Method 2: Place Value

2,000 + 300 + 50 + 7

Method 3: Standard Algorithm

Method 3: Standard Algorithm

First, look at the ones place numbers. If the number on top is smaller than the bottom number, I must regroup before I subtract.

Method 3: Standard Algorithm

Next, look at the tens place numbers. If the number on top is smaller than the bottom number, I must regroup again before subtracting.

Method 3: Standard Algorithm

Now, look at the hundreds place numbers. If the number on top is smaller than the bottom number, I must regroup again before subtracting.

Method 3: Standard Algorithm

Now, subtract the thousands. So, our answer is 3,166.

Let’s Try It!

9,076 - 4,652

Let’s Try It!

45,893 - 12,945

There are 28,708 fans at the first basketball game of the season. There are 8,993 fans at the second basketball game of the season.

How many more fans would need to attend the second basketball game to have the same number of fans as the first game?

Find the difference between 6,345 and 451.

Which is the first step when subtracting 597 from 9,246?

Camille subtracted 3,256 from 6,000 and got 9,256. Which correctly explains the mistake that Camille made and gives the correct answer?

Simone knows that 67 + 34 = 101. How will this help her solve the problem 101 – 34?

Write a number sentence that will correctly solve this problem:

A stadium holds 71,030 people. Thirty minutes before the game started there were 34,761 in the stadium. How many more people would have to come so that all the seats were filled?

Margo was asked to put numbers in the boxes to make this equation correct.

4, 3 – 2,749 = 1,489 Margo doesn't want to use the 'guess and

check' strategy. Which strategy could Margo use?

Subtract:

8,743 – 689 =

Subtract:

6,046 – 39