Round to decimal places or powers of ten. This tool uses the explicitly stated midpoint-away-from-zero rule: −1.5 rounds to −2 at zero decimal places.
Check the stated input format, calculation convention and limits before using the result.
Check the example inputs, then calculate. Your values stay in this browser.
Negative places round tens, hundreds and larger units.
Rounding Calculator validates number, decimal places (−12 to 12) before applying the displayed equation. Negative places round tens, hundreds and larger units.
Rounding Calculator: rounded = sign(x) × floor(|x| × 10^places + 0.5) / 10^places. Input definitions: value = Number; places = Decimal places (−12 to 12). Use the selected convention throughout the calculation.
Rounding Calculator baseline input: Number: 12.345; Decimal places (−12 to 12): 2. Output: Result = 12.35. Substitute these values into the displayed equation to reproduce the result.
Content and calculation reviewed:
Understand the calculation
Choose the place before applying the tie rule. At one decimal place, −1.25 is exactly halfway between −1.2 and −1.3; midpoint-away-from-zero chooses −1.3. Negative places round to tens or hundreds. The engine rounds decimal digits with integer arithmetic to avoid a scaled epsilon changing large integers. A displayed trailing zero communicates the chosen precision.
rounded = sign(x) × floor(|x| × 10^places + 0.5) / 10^places
The detailed guide adds variable definitions, a reproducible example, a practice question and model limitations.
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