Rounding Numbers Calculator
Round a number to any place from millions to millionths, step by step. See the target digit, the deciding digit, and the direction, using Half Away From Zero.
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How to round a number
Rounding replaces a number with a nearby, simpler one at a chosen place — the nearest ten, hundred, tenth, hundredth, and so on. The rule uses only two digits.
The three steps
- Find the target digit in the place you are rounding to.
- Look at the deciding digit — the single digit immediately to its right.
- If the deciding digit is 5 or more, round up; if it is less than 5, round down (keep the target digit). Digits to the right become 0 or are dropped.
Tip: Look at only one digit. Rounding 2.48 to a whole number is 2 — do not round 8 up to make 2.5 and then to 3.
Worked example: 838.274
- To the nearest hundredth (place −2): target digit 7, deciding digit 4 → round down → 838.27.
- To the nearest tenth: deciding digit 7 → round up → 838.3.
- To the nearest hundred: target 8, deciding digit 3 → round down → 800.
Halfway values: Half Away From Zero
When the deciding digit is exactly 5, this calculator rounds away from zero:
- 3250 to the nearest hundred → 3300
- 2.5 to a whole number → 3, and −2.5 → −3
- 0.125 to the nearest hundredth → 0.13
Carrying past a 9
Rounding up a 9 turns it into 0 and carries left:
- 499 to the nearest ten → 500
- 999.9 to a whole number → 1000
Common mistakes
- Chain rounding (2.48 → 2.5 → 3) instead of looking at one digit.
- Rounding a halfway 5 toward zero — Half Away From Zero rounds up in magnitude.
- Forgetting the carry when a 9 rounds up.
To choose a different rule (Half Even, floor, ceiling), use rounding methods; to round to a multiple like the nearest 25, use round to the nearest multiple.
Frequently asked questions
- How do you round a number?
- Find the digit in the place you are rounding to, then look at the single digit immediately to its right. If that digit is 5 or more, round up; if it is less than 5, round down (keep the target digit). Everything to the right becomes zero or is dropped.
- Which digit decides whether I round up or down?
- Only the one digit immediately to the right of the target place. You never round in a chain — 2.48 rounded to the nearest whole number is 2, because the deciding digit is 4, not the 8 further right.
- What is Half Away From Zero rounding?
- When the deciding digit is exactly 5, the number rounds away from zero. So 2.5 rounds to 3 and negative 2.5 rounds to negative 3. This is the everyday rounding taught in school, and it is what this calculator uses.
- How do I round a 5 that is exactly halfway?
- With Half Away From Zero, a trailing 5 always rounds the target digit up in magnitude. 3250 to the nearest hundred is 3300, and 0.125 to the nearest hundredth is 0.13. Banker's rounding would treat some of these differently.
- What happens when rounding up a 9?
- The 9 becomes 0 and carries 1 into the next place to the left, which can ripple. 499 to the nearest ten is 500, and 999.9 to the nearest whole number is 1000.
- How do I round negative numbers?
- Look at the deciding digit exactly as with positive numbers. With Half Away From Zero, a halfway negative number moves away from zero, so negative 2.5 rounds to negative 3.
- What is the difference between rounding and truncating?
- Rounding adjusts the last kept digit based on the next one, while truncating simply drops the rest. 1.466 rounds to 1.47 but truncates to 1.46. Long division to decimals truncates; this calculator rounds.