using System;

using System.Linq;

using System.Collections.Generic;

using System.ComponentModel;

using System.ComponentModel.DataAnnotations;

public class Program

{

    public static void Main()

    {

        var a = new List<int>() { 1, 2, 3 };

        var b = new List<int>() { 5, 1, 2 }; 

​

        var c = a.Select((x, i) => b[i] * x);

        foreach (var value in c)

        {

            Console.WriteLine(value);

        }

    }

}