Not all query operators return a sequence.
The element operators extract one element from the input sequence.
First, Last, and ElementAt all return a single element
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
class Program
{
static void Main()
{
int[] numbers = { 10, 9, 8, 7, 6 };
int firstNumber = numbers.First(); // 10
int lastNumber = numbers.Last(); // 6
int secondNumber = numbers.ElementAt(1); // 9
int lowestNumber = numbers.OrderBy(n => n).First(); // 6
}
}