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Subtracting From Three-Digit Numbers

Look at you. You're already moving ahead to triple-digit numbers in subtraction problems. It's a good thing that the process for solving these problems uses the same ideas you already know.

(1) Subtract one column at a time.
(2) Work from right to left.

Examples (no borrowing):
123 - 2 = 121
456 - 22 = 434
867 - 254 = 613
- or -

867 - 254 613

A Little More Borrowing

They all won't be super-easy, non-borrowing, subtraction problems. We need to give you a challenge. You will have to borrow or regroup in your homework. When you were subtracting two-digit numbers, you were only borrowing from the tens column. Now that you're using three-digit numbers you may be borrowing from the tens, hundreds, or both columns. Here are some examples where you are only borrowing from the tens column...

123 - 5 = 118
478 - 9 = 469
845 - 18 = 827
- or -

845 - 18 827

And some examples where you might be borrowing from the hundreds column...

367 - 71 = 296
729 - 82 = 647
206 - 15 = 191
- or -

206 - 15 191

And then the longest type, where you borrow from both the tens and hundreds columns. These problems have both the ones and tens values of the subtrahend (second number) that are smaller than the minuend (first number) values.

623 - 86 = 537
201 - 15 = 186
- or -

201 - 15 186

You should notice how we borrowed with a zero in the tens column on that last example. You wound up borrowing from the hundreds column and bringing that value all the way over to the ones column.

More Than Three Digits

It will happen eventually that you will need to subtract numbers in the thousands (4-digit), ten thousands (5-digit), and hundred thousands (6-digit). Don't be afraid of the big numbers. The same rules apply to all numbers that you subtract.

• Subtract one number from another and you are left with a difference.
• The difference will always be less than the first number in your problem.
• Practice, practice, practice.

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