How to use (3 steps)
Result
Visualizer
Sign rules (× / ÷)
| a \\ b | + | - |
|---|---|---|
| + | + | - |
| - | - | + |
Same signs give +, different signs give -, and zero yields 0.
FAQ
Why does subtracting a negative turn into addition?
a - (-b) moves to the right by |b| on the number line, so it is equal to a + b. The calculator rewrites subtraction this way and shows the movement step by step.
How do I move on the number line when b is negative?
If b is negative, the arrow points left by |b|. The visual keeps the start, direction, and landing point visible so the sign change near zero is easy to see.
How is the sign decided for multiplication or division?
If the signs match, the result is positive. If they differ, the result is negative. If either value is zero, the result is zero. The 2×2 table highlights the active case.
Can I use commas or full-width digits?
Yes. Commas and common full-width digits are normalized before checking the format and digit limits. Invalid input or division by zero shows a clear error.
Are calculations sent to a server?
No. Everything stays in your browser unless you choose to copy a shareable URL.