Long Subtraction Calculator with Steps
Enter any two whole or decimal numbers and this calculator subtracts them using the standard column (long subtraction) method. Every regrouping step is shown column by column, from the ones place leftward, so you can see exactly where and why borrowing happens. Negative results are handled automatically. Works for large numbers, decimals, and any combination.
What is long subtraction?
Long subtraction (also called column subtraction) is the standard written method for subtracting one number from another. The numbers are stacked vertically, aligned by place value, and you work digit by digit from the rightmost column (ones) toward the left. When a digit in the top number is smaller than the one beneath it, you borrow 1 from the column to the left, increasing the current digit by 10 and reducing the left neighbor by 1. This borrowing process, also called regrouping, is repeated as many times as needed. The result is read from the bottom row of the working.
How to subtract with regrouping (borrowing)
Start at the ones column (rightmost). If the top digit is greater than or equal to the bottom digit, subtract and write the answer below. If the top digit is less than the bottom digit, borrow 1 from the next column to the left: cross out that neighbor, reduce it by 1, and write a small 1 next to the current top digit (making it top digit + 10). Then subtract. If the neighbor to the left is itself a zero, you must keep moving left until you find a non-zero digit, changing each intermediate zero to a 9 along the way. Repeat this process for every column until all digits are handled. When the minuend (top number) is smaller than the subtrahend (bottom number) overall, swap them, compute as normal, and prefix the result with a negative sign.
Subtracting decimals in columns
To subtract decimal numbers using the column method, align the decimal points vertically so they share a column. Pad whichever number has fewer decimal places with trailing zeros on the right so both numbers have the same number of decimal places. Then subtract exactly as you would with whole numbers, treating the decimal point as a separator that appears in the same position in the answer. For example, subtracting 3.7 from 12.45 becomes 12.45 minus 3.70, with the decimal points aligned, and the subtraction proceeds column by column from the hundredths place leftward.
Checking your answer
The fastest check for a subtraction result is to add the difference (answer) back to the subtrahend (second number): if the sum equals the minuend (first number), the subtraction is correct. For example, if 5,472 minus 1,358 gives 4,114, then 4,114 plus 1,358 must equal 5,472. If it does not, at least one column contains an error. This inverse-operation check is reliable for any size of number, including decimals. This calculator shows the verification automatically under the result.
Place value reference
| Column position (from right) | Place name | Value of 1 digit |
|---|---|---|
| 1 | Ones | 1 |
| 2 | Tens | 10 |
| 3 | Hundreds | 100 |
| 4 | Thousands | 1,000 |
| 5 | Ten-thousands | 10,000 |
| 6 | Hundred-thousands | 100,000 |
| 7 | Millions | 1,000,000 |
| -1 (first right of decimal) | Tenths | 0.1 |
| -2 | Hundredths | 0.01 |
| -3 | Thousandths | 0.001 |
Standard column names used during long subtraction, from left (largest) to right (smallest).
Frequently asked questions
What is the difference between the minuend and the subtrahend?
The minuend is the number you start with (the one being subtracted from), and the subtrahend is the number being taken away. In the expression 9 - 4 = 5, nine is the minuend, four is the subtrahend, and five is the difference. Keeping the order correct matters: subtraction is not commutative, so swapping them changes the sign of the result.
What does "borrowing" or "regrouping" mean in subtraction?
When a digit in the top number is smaller than the digit directly below it, you cannot subtract directly. You borrow 1 from the column immediately to the left, which reduces that neighbor by 1 and adds 10 to the current column (because moving one column right is equivalent to multiplying by 10). This process is called regrouping because you are trading one group of ten for ten ones, one group of one hundred for ten tens, and so on.
Can I subtract a larger number from a smaller one?
Yes. When the first number (minuend) is smaller than the second (subtrahend), the result is a negative number. The column method still works: swap the numbers so the larger is on top, subtract as usual, and then attach a negative sign to the result. This calculator handles that automatically and shows the correct signed answer.
How do I subtract decimal numbers in columns?
Align the decimal points in the same column, then pad the number with fewer decimal places by appending trailing zeros on the right until both numbers have equal decimal places. Subtract column by column exactly as with whole numbers, starting from the rightmost decimal place and working left through the decimal point into the integer part. The decimal point appears in the same position in the answer.
What happens if I need to borrow and the next digit is zero?
If the column you want to borrow from is a zero, you cannot reduce it further without going even further left. Continue moving left until you find a non-zero digit, temporarily converting each zero along the way to a 9 (because borrowing 1 from 10 leaves 9 in that column). Once you reach a non-zero digit, reduce it by 1 and cascade the borrowed value back rightward. This calculator handles all such chain-borrowing cases automatically.