Building a Random number generator in Windows Forms [duplicate]

This question already has an answer here:

• What is an IndexOutOfRangeException / ArgumentOutOfRangeException and how do I fix it? 2 answers

SO I'm creating a random number generator with multiple windows but when I use first Form it gives me a problem in this section.

list_Random.Items.Clear();
        int cuantos = Int32.Parse(txt_numero_a_generar.Text);
        int generador = Int32.Parse(txt_raiz.Text);
        int operacion = 0;
        for (int i = 0; i < cuantos; i++ )
        {
            operacion = generador * generador;
            string tempOperacion = operacion.ToString();
            if(  (tempOperacion.Length)%2!= 0  )
            {
                tempOperacion = "0" + tempOperacion;
            }
            int x = (tempOperacion.Length) / 2;
            char[] numbers = tempOperacion.ToCharArray();
            string filtrado = (numbers[x - 2]).ToString() + numbers[x - 1].ToString() + numbers[x].ToString() + numbers[x + 1].ToString();
            generador = Int32.Parse(filtrado);
            float numRando = (float)generador / 10000;
            list_Random.Items.Add(numRando.ToString());
        }
    }

It says that "An unhandled exception of type 'System.IndexOutOfRangeException' occurred in AppMetodos.exe" In this section.

string filtrado = (numbers[x - 2]).ToString() + numbers[x - 1].ToString() + numbers[x].ToString() + numbers[x + 1].ToString();