Spoken Numbers

/// <summary>
/// Format a number as it would be said.
/// </summary>
/// <param name="aValue">Number to format.</param>
/// <returns>Formatted number with suffix.</returns>
public static string AsSaid(this int aValue)
{
    string suffix = "th";
    if (aValue % 10 == 1 && aValue != 11)
    {
        suffix = "st";
    }
    else if (aValue % 10 == 2 && aValue != 12)
    {
        suffix = "nd";
    }
    else if (aValue % 10 == 3 && aValue != 13)
    {
        suffix = "rd";
    }
    return string.Format("{0}{1}", aValue, suffix);
}