Subtraction Calculator – Subtract Numbers Instantly
Find the difference between two numbers with our free subtraction calculator. Enter any two values and get instant results – no sign-up required.
Enter the first number
This is the number you're subtracting from (called the minuend). It can be positive or negative, whole or decimal.
Enter the second number
This is the number being subtracted (called the subtrahend). Enter any value you want to subtract from the first number.
Get your result
Click Calculate to see the difference. The result appears instantly below the input fields.
Subtraction is one of the four fundamental operations in arithmetic. It tells you how much is left when you take one quantity away from another, or how much greater one number is than another.
The number you start with is called the minuend. The number you take away is the subtrahend. The result is called the difference. For example, in 15 – 7 = 8, fifteen is the minuend, seven is the subtrahend, and eight is the difference.
Subtraction is the opposite of addition. If you know that 8 + 7 = 15, then you automatically know that 15 – 7 = 8. This relationship makes subtraction easier to understand and verify.
| Property | Formula | Example |
|---|---|---|
| Identity | a – 0 = a | 25 – 0 = 25 |
| Self-Subtraction | a – a = 0 | 17 – 17 = 0 |
| Non-Commutative | a – b ≠ b – a | 10 – 3 = 7, but 3 – 10 = -7 |
| Non-Associative | (a – b) – c ≠ a – (b – c) | (10 – 5) – 2 = 3, but 10 – (5 – 2) = 7 |
| Inverse of Addition | a – b = a + (-b) | 8 – 3 = 8 + (-3) = 5 |
Positive minus Positive
Subtract normally. If the second number is larger, the result is negative.
15 – 8 = 7 | 8 – 15 = -7
Positive minus Negative
Subtracting a negative is the same as adding. The two minus signs become a plus.
10 – (-5) = 10 + 5 = 15
Negative minus Positive
Add the absolute values and keep the negative sign.
-8 – 3 = -11
Negative minus Negative
Change the second minus to plus, then follow addition rules for negatives.
-10 – (-4) = -10 + 4 = -6
Calculating Change
Subtract the purchase amount from what you paid to find your change.
Finding Temperature Differences
Subtract the low temperature from the high to see the daily range.
Tracking Weight Loss
Subtract current weight from starting weight to measure progress.
Budget Planning
Subtract expenses from income to see what's left for savings.
Time Calculations
Subtract start time from end time to find duration.
What is subtraction?
Subtraction is the arithmetic operation of finding the difference between two numbers by taking one away from the other. It's the opposite of addition and is used to calculate how much remains, how much more is needed, or how much greater one value is than another.
What are the parts of a subtraction problem?
A subtraction problem has three parts: the minuend (the number being subtracted from), the subtrahend (the number being subtracted), and the difference (the result). In 20 – 8 = 12, twenty is the minuend, eight is the subtrahend, and twelve is the difference.
Can you subtract a larger number from a smaller one?
Yes. When you subtract a larger number from a smaller one, the result is negative. For example, 5 – 12 = -7. This represents moving left past zero on the number line.
Why is subtracting a negative the same as adding?
Think of it this way: if losing $5 is represented as -5, then "taking away a loss of $5" means you're actually gaining $5. Mathematically, 10 – (-5) = 10 + 5 = 15. Two negatives make a positive in subtraction.
How do you check a subtraction answer?
Add the difference back to the subtrahend. If your subtraction is correct, you should get the original minuend. For example, if 25 – 9 = 16, check by adding 16 + 9 = 25.
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