What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20

Question

My problem is the answer of this code. I know it's working but the answer is taking so long and the numbers still going.

class Program
{
    static void Main(string[] args)
    {
        long Number = 1;
        for (int i = 1; i <= 20; i++)
        {
            if (Number % i != 0)
            {
                i = 1;
                Number++;
            }
            Console.WriteLine(Number);
        }
        Console.Read();
    }
}

I want the console write the last number but i dont know what to do.

Answer 1

 static void Main(string[] args)
        {
            Console.WriteLine(problem().ToString());

}

    public static int problem()
            {
                int i =1;
                bool found = false;
                while (!found)
                {
                    i += 1;
                    bool isDividable = true;
                    for (int j = 1; j <= 20; j++)
                    {
                        if (i % j != 0)
                        {
                            isDividable = false;
                            break;
                        }
                    }
                    if (isDividable)
                    {
                        found = true;
                    }
                }
                return i;
            }