Rounding numbers

How to:

Here’s the round-trip ticket for rounding numbers in C#:

using System;

public class RoundingExamples
    public static void Main()
        double originalNumber = 123.4567;

        // Round to nearest whole number
        double rounded = Math.Round(originalNumber);
        Console.WriteLine(rounded); // Output: 123

        // Specify number of decimal places
        double roundedTwoDecimalPlaces = Math.Round(originalNumber, 2);
        Console.WriteLine(roundedTwoDecimalPlaces); // Output: 123.46

        // Round up regardless of the next digit
        double roundedUp = Math.Ceiling(originalNumber);
        Console.WriteLine(roundedUp); // Output: 124

        // Round down regardless of the next digit
        double roundedDown = Math.Floor(originalNumber);
        Console.WriteLine(roundedDown); // Output: 123

Deep Dive

Back in the day, rounding was a no-brainer for trimming computational costs. Every cycle counted, and trimming numbers saved precious time. Fast-forward to modern C#, and it’s about managing doubles and decimals’ notorious predisposition to precision errors and display quirks.

Beyond Math.Round, Math.Floor, and Math.Ceiling, the MidpointRounding enum lets us dictate the fate of poor, middle-sitting digits—it’s the crossroads between banking rules and the playground fairness of “round half up”.

For tougher crowds, like serious math or finance applications, we’ve got decimal over double, cutting down on rounding drama by offering higher precision—less rounding, less problems.

See Also