Función IsNumber Ejercicio C# - Curso de Programación C# (C Sharp)

using System;
public class exercise124
{
    public static bool IsNumber(string text)
    {
        for (int i = 0; i < text.Length; i++)
        if (text[i] < '0') || (text[i] > '9')
            return false;

        return true;
    }


    public static void Main()
    {
        Console.WriteLine( IsNumber("12") );
    }
}