using System;
                    
public class Program
{
    public static void Main()
    {
        int ondanbuyukolan = 0;
int[] dizi = { 1, 5, 7, 12, 21, 18, 9, 8 };
for (int i = 0; i < dizi.Length; i++)
{
if (dizi[i]<10)
{
ondanbuyukolan++;
}
}
        Console.WriteLine(ondanbuyukolan);
    }
}

/* eklenmesi gerekenler
using System;
using System.Data;
using System.Linq;
*/
public Tuple<int, int> GetCount(DataTable dt, int min, int max)
{
var result = dt.AsEnumerable().Where(num => num.Field<int>("number") >= min && num.Field<int>("number") <= max);
int count = result.Count();
int inCount = result.Sum(numCount => numCount.Field<int>("COUNT(*)"));
return new Tuple<int, int>(count, inCount);
}

var count = GetCount(datatable, 1, 10);
Console.WriteLine("Belirlenen aralıkta {0} sonuç bulundu, toplam adet {1}.", count.Item1, count.Item2);