using System;

public static class Program

{

    public static double RoundToSignificantDigits(this double value, int digits)

    {

        if (value == 0.0d || double.IsInfinity(value) || double.IsNaN(value))

            return value;

​

        double scale = Math.Pow(10, Math.Floor(Math.Log10(Math.Abs(value))) + 1);

        return scale*Math.Round(value/scale, digits);

    }

    public static void RunTest(double value, int num_digits) 

    {

        double rounded_double = RoundToSignificantDigits(value, num_digits);

        Console.WriteLine("Double : Value {0}, Rounded to {2} digits = {1}", value, rounded_double, num_digits);

    }

​

    public static void Main()

    {

        RunTest(28.45, 2);

    }

}