Guide des regles d'arrondi et des chiffres significatifs

Standard rounding usually rounds negative numbers "away from zero" (e.g., -2.5 becomes -3). However, "Ceiling" always rounds toward positive infinity (-2.5 becomes -2), while "Floor" always rounds toward negative infinity (-2.5 becomes -3).

In a number like 1200, it's unclear if there are 2, 3, or 4 sig figs. Scientists use scientific notation to remove this ambiguity: 1.2 x 10³ has 2 sig figs, while 1.200 x 10³ has 4.

Yes. Our Rounding Calculator includes a "Half-to-Even" mode specifically for financial and statistical work where bias must be minimized.

The Five Rule is the most common standard: if the last digit is 5 or more, you round up. If it is less than 5, you round down (keep the current digit).

Rounding at each step introduces "rounding error" that accumulates. You should keep all decimals in your calculator during intermediate steps and only round the final result.

Truncation simply cuts off digits after a certain point without adjusting the last digit (it's the same as "Rounding Down" for positive numbers), whereas rounding adjusts the last digit based on the value being removed.

In engineering and construction, overestimating precision can lead to failure. If a beam is measured to within 1cm, claiming its length is 10.552 meters implies a precision of 1mm, which is dangerous miscommunication.