Double - Log10

Returns the base 10 logarithm of a specified number.

Try it

public static void Main()
{
    double[] numbers = {-1, 0, .105, .5, .798, 1, 4, 6.9, 10, 50, 100, 500, 1000, Double.MaxValue};

    foreach (double number in numbers)
    {		
		// C# Extension Method: Double - Log10
        Console.WriteLine("The base 10 log of {0} is {1}.", 
                       number, number.Log10());
    }
}

View Source 
using System;

public static partial class Extensions
{
    /// <summary>
    ///     Returns the base 10 logarithm of a specified number.
    /// </summary>
    /// <param name="d">A number whose logarithm is to be found.</param>
    /// <returns>
    ///     One of the values in the following table.  parameter Return value Positive The base 10 log of ; that is, log
    ///     10. Zero Negative Equal to Equal to.
    /// </returns>
    public static Double Log10(this Double d)
    {
        return Math.Log10(d);
    }
}