Addition and Subtraction

Solving Stacked Subtraction Problems

If you feel comfortable with the subtraction skills from Lesson 3, you're ready to start solving stacked subtraction problems.

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  Let's try to solve 49 - 7.

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  With all stacked subtraction problems, we start with the digits that are farthest to the right. Here, we'll begin with 9 and 7.

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  9 - 7 = 2. The difference is 2. It's important to write 2 directly beneath the digits we just subtracted.

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  Now let's find the difference of the digits to the left. The top digit is 4, but there's nothing beneath it.

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  4 minus nothing is 4, so we'll write 4 beneath the line.

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  Our result is 42. 49 - 7 = 42.

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  Let's see how this works with another problem: 88 - 62.

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  As always, start with the digits that are farthest to the right. Here, they are 8 and 2.

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  8 - 2 = 6. Make sure to write 6 below the line.

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  Next, find the difference of the digits to the left, 8 and 6.

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  8 - 6 is 2. Write 2 below the line.

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  The answer is 26. 88 - 62 = 26.

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In the slideshow, you saw that stacked subtraction problems are always solved from right to left. The expressions below are solved the same way. First, the bottom right digit is subtracted from the top right digit. Then, the bottom left digit is subtracted from the top left digit.

 Now you try it. Solve these stacked subtraction problems.

Subtracting Larger Numbers

Stacked subtraction can also be used for finding the difference of larger numbers. No matter how many digits there are, you subtract the same way every time — from right to left.

Try it. These subtraction problems have larger numbers. Practice solving them from right to left.