Understand the subject
How do decimal places control rounding?
Decimal-place rounding keeps a chosen number of digits after the decimal marker and decides what to do with the next digit.
Use it for a stated display precision such as money, measurements, or a requested number of decimal places.
The key rule
What stays true
2.5 → 2; 3.5 → 4
See the idea
Visual explanation
2.5 → 23.5 → 4retain the even digit at an exact tie
Example
Apply it
At an exact tie, half-even makes the retained digit even.
A decimal-place count is different from a significant-figure count.
Quick guide
How to use this calculator
- Enter a finite decimal.
- Choose 0–100 decimal places.
- Read the half-even result with the requested written scale.
Calculation method
Half-even controls exact ties
Values below half stay and values above half move away from zero. At an exact tie, the retained digit is made even.
Worked example
Two exact ties
Half-even prevents a one-direction tie bias across repeated rounding.
2.5 → 2; 3.5 → 4
Supported inputs
Precision and limits
Exact decimal input
Finite decimals use integer-scaled arithmetic, with no binary floating-point conversion.
Input boundary
Unless stated otherwise, use at most 200 digits total and 100 digits after the decimal marker.
