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 on big number problems!

categories

Arithmetic, Whole Numbers and Operations

subject
Math
learning style
Auditory, Visual
personality style
Otter
Primary (K-2), 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 you subtract whole numbers, you 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 you subtract. The greater number needs to be the starting number.

Remember to line up the decimals and place values if you are subtracting money.

Watch the video below to explore regrouping in subtraction.

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

Follow these steps 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.
1. Begin in the one's place and subtract. Regroup if needed.
1. Move to the left and subtract the tens and hundreds.
1. Check your work by adding up. Add the two bottom numbers to be sure the sum equals the top number.

Practice with this problem.

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Rewrite the problem with the greater number on top.

6

Subtract and regroup as needed.

4

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

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• How do you know if you need to regroup?
• How can you use a model or different strategy to help with subtraction?
• What happens if you don't regroup?

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

Interactive Video