Subtraction: 3-digit

Contributor: Erika Wargo. Lesson ID: 12215

Is there a "difference" between addition and subtraction? If you can subtract 1-digit numbers can you subtract 3-digit numbers? Learn to use subtraction in addition to addition on big number problems!

categories

Elementary

subject
Math
learning style
Auditory, Visual
personality style
Otter
Grade Level
Intermediate (3-5)
Lesson Type
Skill Sharpener

Lesson Plan - Get It!

Audio:

The new bike you want costs $250 and you have $116 in your bank account. How much more money do you need before you can buy the bike?

Did you know that subtraction is the inverse, or opposite of, addition?

The answer to a subtraction problem is called the "difference." When we subtract whole numbers, we align the digits by place value. Subtract the bottom number from the top number and regroup when necessary. But it is important to remember that order matters when we subtract. The greater number needs to be the starting number. If you are subtracting money, remember to line up the decimals and place values.

Watch Subtraction with Regrouping Song by NUMBEROCK to review how to regroup in subtraction:

 

After the video, discuss with a parent or teacher:

  • What does regrouping mean?
  • How do you know if you need to regroup?

To subtract whole numbers:

  1. Rewrite the problem vertically and line up the place values and decimal points. Be sure the greater number is the top number.
  2. Begin in the ones place and subtract. Regroup if needed.
  3. Move to the left and subtract the tens and hundreds.
  4. Check your work by "Adding up." Add the two bottom numbers to be sure the sum equals the top number.

$250 - $116 =

Rewrite the problem, with the greater number on top:

           
   

$

2

5

0

 

-

$

1

1

6

           

 

Subtract and regroup as needed:

       

4

1

   

$

2

5

0

 

-

$

1

1

6

   

$

1

3

4

 

"Add up" and check your work. $250 is the number you started with, so you are correct!

       

1

 
   

$

1

3

4

 

+

$

1

1

6

   

$

2

5

0

 

Discuss with a parent or teacher how you know if you need to regroup. Explain how you can use a model or different strategy to help with subtraction. What happens if you don’t regroup?

In the Got It? section, you will practice three-digit subtraction with games!

Elephango's Philosophy

We help prepare learners for a future that cannot yet be defined. They must be ready for change, willing to learn and able to think critically. Elephango is designed to create lifelong learners who are ready for that rapidly changing future.