How this calculator works
The neighbouring multiples of one hundred bracket the input. For a positive whole number, inspect the tens digit and any smaller digits: less than fifty above the lower hundred favours that hundred, and more than fifty favours the next. Exactly fifty is a tie. The table shows the actual decimal distances, including negative inputs, rather than relying only on a digit mnemonic.
Formula
Candidates are 100 × floor(x/100) and the next multiple of 100. Compare their distances to x. At a tie, apply the selected rule. Exact multiples return themselves.
Worked example
1250 is halfway between 1200 and 1300. Half-even chooses 1200 because 12 is even; half-up chooses 1300. For -1250, half-up chooses -1300.
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Frequently asked questions
Does half-even check the last digit of the answer?
It checks the integer multiple of 100. The lower candidate 1200 is 12 times 100, an even multiple, so it wins the example tie.
What is the difference between up and ceiling?
Up moves away from zero. Ceiling moves toward plus infinity. They agree for positive inputs and can disagree for negative inputs.
Can I enter a very long integer?
Yes. Up to 200 characters of plain decimal text are retained exactly. Omit commas, spaces within the number and scientific notation.