Use LINQ to perform calculations

SumNumbers.cs

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

namespace LINQSum
{
    public class SumNumbers
    {
        private int[] numberList = {1, 2, 4, 8, 16, 32}; 

        public int SumUsingLinq()
        {
            return numberList.Sum(num => num);
        }

        public int SumUsingForeach()
        {
            var sum = 0;
            foreach (int num in numberList)
            {
                sum += num;
            }
            return sum;
        }

        public double SumSquaresUsingLinq()
        {
            return numberList.Sum(num => Math.Pow(num, 2));
        }

        static void Main(string[] args)
        {
            var sum = new SumNumbers();
            var linqSum = sum.SumUsingLinq();
            var foreachSum = sum.SumUsingForeach();
            var sumSquares = sum.SumSquaresUsingLinq();

            Console.WriteLine("LINQ Sum: {0}", linqSum);
            Console.WriteLine("ForeachSum: {0} ", foreachSum);
            Console.WriteLine("SumSquares: {0} ", sumSquares);
            Console.ReadKey();
        }
    }
}

SumNumbersTests.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using NUnit.Framework;


namespace LINQSum.Tests
{
    [TestFixture]
    public class SumNumbersTests
    {
        [Test]
        public void ShouldAddAllValuesUsingForeach()
        {
            var sum = new SumNumbers();
            Assert.AreEqual(63, sum.SumUsingForeach());
        }

        [Test]
        public void ShouldAddAllValuesUsingLinqExpression()
        {
            var sum = new SumNumbers();
            Assert.AreEqual(63, sum.SumUsingLinq());
        }

        [Test]
        public void LinqExpressionAndForeachSumShouldBeEqual()
        {
            var sum = new SumNumbers();
            Assert.AreEqual(sum.SumUsingForeach(), sum.SumUsingLinq());
        }

        [Test]
        public void ShouldSumTheSquaresOfAllValuesUsingLinqExpression()
        {
            var sum = new SumNumbers();
            Assert.AreEqual(1365.0, sum.SumSquaresUsingLinq());
        }
    }
}