Extend.cs

using System.Globalization;

namespace IsThirteen
{
    public static class Extend
    {
        public static bool IsThirteen(this int x)
        {
            return x == 13;
        }

        public static bool IsThirteen(this double x)
        {
            return Math.Abs(x - 13.0d) == 0;
        }

        public static void DoIfThirteen(this int x, Action action)
        {
            if (x == 13) action.Invoke();
        }

        public static void DoIfThirteen(this double x, Action action)
        {
            if (Math.Abs(x - 13.0d) == 0) action.Invoke();
        }

        public static void DoIfThirteenOrNot(this int x, Action actionTrue, Action actionFalse)
        {
            if (x == 13) actionTrue.Invoke();
            else actionFalse.Invoke();
        }

        public static void DoIfThirteenOrNot(this double x, Action actionTrue, Action actionFalse)
        {
            if (Math.Abs(x - 13.0d) == 0) actionTrue.Invoke();
            else actionFalse.Invoke();
        }

        public static double Rough(this double x)
        {
            if (x is >= 12.5 and < 13.5)
                return 13;
            else
                return x;
        }

        public static bool Within(this int x, int interval)
        {
            if (x >= 13 - interval && x <= 13 + interval)
                return true;
            return false;
        }

        public static bool Within(this double x, double interval)
        {
            if (x >= 13 - interval && x <= 13 + interval)
                return true;
            return false;
        }

        public static bool Without(this int x, int interval)
        {
            if (x >= 13 - interval && x <= 13 + interval)
                return false;
            return true;
        }

        public static bool Without(this double x, double interval)
        {
            if (x >= 13 - interval && x <= 13 + interval)
                return false;
            return true;
        }

        public static double Up(this double x)
        {
            if (x is >= 12.5 and <= 13)
                return 13d;
            else
                return x;
        }

        public static double Down(this double x)
        {
            if (x is > 13 and <= 13.5)
                return 13d;
            else
                return x;
        }

        public static int HaveThirteen(this int x)
        {
            if (x.ToString().Contains("13"))
                return 13;
            else
                return x;
        }

        public static double HaveThirteen(this double x)
        {
            if (x.ToString(CultureInfo.InvariantCulture).Contains("13"))
                return 13;
            else
                return x;
        }

        public static void DoIfHaveThirteen(this int x, Action action)
        {
            if (x.HaveThirteen() == 13)
                action.Invoke();
        }

        public static void DoIfHaveThirteen(this double x, Action action)
        {
            if (Math.Abs(x.HaveThirteen() - 13.0d) == 0)
                action.Invoke();
        }

        public static void DoIfHaveThirteenOrNot(this int x, Action actionTrue, Action actionFalse)
        {
            if (x.HaveThirteen() == 13)
                actionTrue.Invoke();
            else
                actionFalse.Invoke();
        }

        public static void DoIfHaveThirteenOrNot(this double x, Action actionTrue, Action actionFalse)
        {
            if (Math.Abs(x.HaveThirteen() - 13.0d) == 0)
                actionTrue.Invoke();
            else
                actionFalse.Invoke();
        }

        public static double Have(this double x)
        {
            if (x.ToString(CultureInfo.InvariantCulture).Contains("13"))
                return 13d;
            else
                return x;
        }

        public static int Multiply(this int x, int y)
        {
            return x * y;
        }

        public static double Multiply(this double x, int y)
        {
            return x * y;
        }

        public static int Pow(this int x, int times)
        {
            var result = 1;
            for (int i = 0; i < times; i++)
            {
                result *= x;
            }

            return result;
        }

        public static double Pow(this double x, int times)
        {
            var result = 1.0d;
            for (int i = 0; i < times; i++)
            {
                result *= x;
            }

            return result;
        }

        public static int DivideBy(this int x, int y)
        {
            return x / y;
        }

        public static double DivideBy(this double x, double y)
        {
            return x / y;
        }

        public static int Plus(this int x, int y)
        {
            return x + y;
        }

        public static double Plus(this double x, double y)
        {
            return x + y;
        }

        public static int Minus(this int x, int y)
        {
            return x - y;
        }

        public static double Minus(this double x, double y)
        {
            return x - y;
        }

        public static bool And(this bool x, bool y)
        {
            return x && y;
        }

        public static bool Or(this bool x, bool y)
        {
            return x || y;
        }

        public static bool Not(this bool x)
        {
            return !x;
        }

        public static void DoIfTrue(this bool x, Action action)
        {
            if (x)
                action.Invoke();
        }

        public static void DoIfTrueOrFalse(this bool x, Action actionTrue,Action actionFalse)
        {
            if (x)
                actionTrue.Invoke();
            else
                actionFalse.Invoke(); ;
        }
    }
}