Arrondis et marges d'erreur (intermédiaire vs final)

Where to round

The same rounding place and method apply to both tabs.

Rounding method Keep trailing zeros Teacher mode

Rounded result

Original vs rounded value with error band.

We highlight both the place you round to and the digit you look at for the rounding decision.

A

First operator

B

Second operator

C

Rounding points Round inputs first (A,B,C) Round the intermediate (A op1 B)

Use the shared rounding settings above. Both scenarios use the same place and method so the comparison stays fair.

Difference (B−A):

Pourquoi diffèrent-ils ?

If you round midway, the rounding error is carried into the next operation and can accumulate or amplify.

Round to any decimal or integer place, with the digit you inspected highlighted.
See the maximum error and the possible true-value band on a number line.
Compare intermediate vs final rounding on (A op1 B) op2 C templates.
Copy a shareable URL or LaTeX, download the error-band SVG, and switch to teacher mode.

Quel chiffre regarder pour arrondir à la n-ième décimale ?

Look at the digit one place to the right of where you round. If it is 5 or more, round up; otherwise round down.

Comment arrondir à la dizaine la plus proche ?

Use the ones place as the decision digit. For example, 368 becomes 370 (error ±5).

Comment exprimer l’intervalle d’erreur d’une approximation ?

With half-up rounding, half of the unit is the maximum absolute error. Rounding to 1 decimal gives ±0.05, so the true value is within that band.

Pourquoi l’arrondi au milieu peut-il changer le résultat ?

Once a rounded value is used in the next operation, its error can accumulate or be amplified, leading to a different final result.

Comment l’arrondi des nombres négatifs est-il géré ?

We use “away from zero” half-up. −1.5 becomes −2, while −1.25 becomes −1.

Ma saisie est-elle envoyée à un serveur ?

No. Everything runs locally in your browser, including the charts.