using System;

using System.Linq;

using System.Linq.Expressions;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        var numbers = new List<int> { 1, 2, 3, 4 }.AsQueryable();

        var param1 = Expression.Parameter(typeof(int), "a");

        var multiplier = Expression.Constant(10, typeof(int));

        var multiplyExpr = Expression.Multiply(param1, multiplier);

        var convertExpr = Expression.Convert(param1, typeof(double));

        var methodCall = typeof(Math).GetMethod("Sqrt", new[] { typeof(double) });

        var sqrtExpr = Expression.Call(methodCall, convertExpr);

        // var lambdaExpr = Expression.Lambda<Func<int, int>>(multiplyExpr, param1);

        var lambdaExpr = Expression.Lambda<Func<int, double>>(sqrtExpr, param1);

        var total = numbers.Select(lambdaExpr);

        foreach (var element in total)

        {

            Console.WriteLine(element);

        }

        Console.WriteLine();

        var method = lambdaExpr.Compile();

        Console.WriteLine(method(144));

    }

}