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Subtraction Calculator

a minus b equals the difference

Solution

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Traditional Subtraction

Traditional subtraction lines up digits by place value and works from right to left. When the top digit is too small, you regroup by borrowing 1 from the next place value to the left.

a - b = difference

How It Works

Traditional subtraction lines up digits by place value and subtracts one column at a time from right to left. If the top digit is smaller than the bottom digit, you regroup by borrowing from the next place value to the left. This calculator shows the regrouped digits in red so you can follow every borrowing step.

Example Problem

Subtract 402 - 178:

  1. Line up the numbers so hundreds, tens, and ones stay in the same columns.
  2. Ones column: 2 is smaller than 8, so borrow across the tens column. The 4 hundreds becomes 3 hundreds, the tens becomes 9, and the ones becomes 12.
  3. Subtract the ones: 12 - 8 = 4.
  4. Subtract the tens: 9 - 7 = 2.
  5. Subtract the hundreds: 3 - 1 = 2.

Result: 224

Key Concepts

Traditional subtraction depends on place value. Borrowing does not change the total amount; it only rewrites one place value as ten of the next smaller place value. The same regrouping idea works for decimals too, as long as the decimal points are lined up before subtracting.

Applications

  • Elementary math education: teaching regrouping and place-value reasoning
  • Bookkeeping: checking differences between balances, totals, and adjustments
  • Measurement and budgeting: finding how much remains after part of a total is used

Common Mistakes

  • Misaligning place values — tens must subtract from tens and hundredths must subtract from hundredths
  • Borrowing from the wrong column — you always regroup from the nearest place value to the left that still has value to lend
  • Forgetting to change the borrowed-from digit — when you borrow 1, the digit to the left decreases by 1

Frequently Asked Questions

How do you subtract with borrowing step by step?

Line up the digits by place value and subtract from right to left. When the top digit is smaller than the bottom digit, borrow 1 from the next column to the left, add 10 to the current column, and then subtract. Repeat until every column is finished.

Can you subtract decimals with borrowing?

Yes. First line up the decimal points so tenths subtract from tenths and hundredths subtract from hundredths. Then borrow across decimal place values exactly the same way you would with whole numbers.

What if the second number is larger in subtraction?

The result is negative. This calculator still shows the borrowing work using the larger absolute value on top, then applies a minus sign to the final answer so the arithmetic stays easy to follow.

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