Rounding Calculator: Decimals & Whole Numbers
Round numbers to a chosen number of decimal places.
Rounding Calculator
Round numbers to specified decimal places
Tips:
- • Precision: 0 = nearest whole number, 1 = one decimal place
- • Maximum precision: 10 decimal places
Rounding Rules (Quick)
Look at the digit right after the place you want to keep:
- If it’s 5 or more → round up
- If it’s 4 or less → keep the same
Examples
| Number | Decimals | Result | Why |
|---|---|---|---|
| 3.14159 | 2 | 3.14 | Next digit is 1 (round down) |
| 2.675 | 2 | 2.68 | Next digit is 5 (round up) |
| 9.99 | 0 | 10 | Rounding to whole number |
How to Use
- 1Enter your number.
- 2Enter how many decimals you want to keep (0 means whole number).
- 3Calculate to get the rounded result.
Common Mistakes
- Confusing rounding with truncation (cutting off digits).
- Rounding too early in multi-step calculations.
- Floating-point quirks (some decimals like 2.675 can behave oddly in code).
Rounding Calculator FAQs
Q
How does rounding work?
Look at the next digit: 5 or more rounds up, 4 or less stays the same.
Q
What does rounding to 0 decimals mean?
It means rounding to the nearest whole number.
Q
How do I round to the nearest tenth?
Set decimals to 1.
Q
How do I round to the nearest hundredth?
Set decimals to 2.
Q
What is the difference between rounding and truncating?
Rounding may change the last digit; truncating just cuts off extra digits.
Q
Why do some decimals round oddly in code?
Because floating-point math stores some decimals approximately.
Q
Should I round during multi-step calculations?
Usually no. Round at the end to reduce accumulated error.
Q
What is “round half up”?
It means values ending in 5 round up (e.g., 2.5 → 3).
Q
Can negative numbers be rounded?
Yes, rounding rules still apply to the magnitude and direction.