Le guide ci-dessous n'est pas encore disponible en français et s'affiche en anglais. Le calculateur lui-même est entièrement traduit.
Comment utiliser ce calculateur
- Enter the number (use a dot for decimals).
- Choose decimal places, significant figures or a place value, and how many.
- Choose a rounding method. Half up is the usual school method.
Formule
Rounding is done in exact decimal arithmetic, so 2.675 rounds to 2.68 (some software gives 2.67 because of binary floating point).
Half up: 2.5 → 3, −2.5 → −3 (half away from zero)
Half even (banker's): 2.5 → 2, 3.5 → 4
Down (truncate): 2.9 → 2; Floor: −2.1 → −3
Examples
- 3.14159 to 2 decimal places = 3.14.
- 0.004567 to 2 significant figures = 0.0046.
- 1,234 to the nearest 100 = 1,200.
Questions fréquentes
What are significant figures?
The digits that carry meaning about precision, starting from the first non-zero digit. 0.00456 has three significant figures.
Why use banker's rounding?
Rounding halves to the nearest even digit avoids a systematic upward bias when many values are rounded and summed. It's used in finance and in the IEEE 754 standard.
What's the difference between round down and floor?
Round down (truncate) moves toward zero; floor moves toward negative infinity. They differ only for negative numbers.