public class Program
{
    public static async Task PrintNumber(int number)
    {
        for(var i = 0; i < 10; i++)
        {
            Console.WriteLine(number);
            await Task.Delay(0);
        }
    }

    public static void Main(string[] args)
    {
        const int count = 10;
        var tasks = new Task[count];

        for (var i = 0; i < count; i++)
            tasks[i] = PrintNumber(i);
    }
}