Sum in Lambda Expressions in C#

using System;
using System.Collections.Generic;
using System.Linq;

namespace NilPointer
{
    class Program
    {
        static void Main(string[] args)
        {
            var numbers = new List<int> {
                50, 2, -7, 11,-9, 26, 6, 42
            };

            var sum1 = numbers.Sum(number => number);
            Console.WriteLine("Sum 1: " + sum1);

            var sum2 = numbers.Where(number => number > 0).Sum(number => number);
            Console.WriteLine("Sum 2: " + sum2);

            Console.ReadLine();
        }
    }
}

Output

Sum 1: 121
Sum 2: 137