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Math

Rounding Calculator

Round a decimal to a chosen number of places, with nearest, upward or downward rounding.

Exact method explained belowEditable inputs

Set up your calculation

Runs on your device

SOLUTION

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter decimal number, decimal places, rounding rule.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

Scale the entered decimal using integer arithmetic, apply the selected rounding rule, and restore the decimal point. Nearest ties move away from zero.

A WORKED EXAMPLE

123.456 rounded to two places is 123.46. Under nearest rounding, −1.25 rounded to one place is −1.3.

What to keep in mind

Plain decimal notation only: no thousands separators or scientific notation. At most 60 digits are accepted. Up and down refer to positive and negative infinity, not always away from or toward zero.

Common questions

How is a negative midpoint rounded?

Nearest rounding uses ties away from zero, so −2.5 rounds to −3 at zero decimal places.

Does the calculation use binary floating-point rounding?

No. It operates on the entered decimal digits with integer arithmetic.

Methodology maintained by ClarityKit. How these tools are built and checked.