C#

Excel.Application app = new Microsoft.Office.Interop.Excel.Application(); 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CustomException
{
    class Program
    {
        static void Main(string[] args)
        {
            ArithmeticUtilityException utility = new ArithmeticUtilityException();
            ///Decimal myNumber = ArithmeticUtilityException.???
        }
    }

    public class ArithmeticUtilityException : ApplicationException
    { 
        public ArithmeticUtilityException() : base() {}
        public ArithmeticUtilityException(string message) : base(message) {}
        public ArithmeticUtilityException(string message, Exception inner) : base(message, inner) {}
    }

    public static class ArithmethicUtility
    {
        public decimal Divide(decimal number, decimal divisor)
        {
            try
            { return number / divisor; }
            catch (Exception err)
            {
                /*  
                 * Create an instance of the specialized exception class, and, 
                 * place the original error in the InnerException property. 
                 */
                ArithmeticUtilityException errNew = new ArithmeticUtilityException("Divide by zero", err);
                throw errNew;
            }
        }
    }
}