Q:

How to multiply numbers from list?

I want to multiply numbers in my list but don't know how to solve that problem. My code works, well numbers are in the list except for numbers which are less ore equal to zero. I write a produkt (engl, product) variable but don't have an idea where and how to use it. User stop program pressing number 0 and then pop-up a message produkt brojeva je: (engl. product of numbers is:) and then should multiply numbers from the list. Here is my code.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Vjezba11_kolokvij1
{
    class Program
    {
        static void Main(string[] args)
        {
            int broj;

            List<int> produktBrojeva = new List<int>();

            do
            {
                Console.WriteLine("Unesite broj: ");
                int.TryParse(Console.ReadLine(), out broj);

                if (broj <= 0)
                {
                    Console.WriteLine("Krivi unos.");
                }
                else
                {
                    produktBrojeva.Add(broj);
                }
            } while (broj != 0);
            Console.WriteLine();

            int produkt;

            for (int i = 0; i < produktBrojeva.Count; i++)
            {
                Console.WriteLine(produktBrojeva[i]);
            }
        }
    }
}

A:

Hope this solves your problem. It's basically your code and i made some minor changes. Although it works, I recommend to use the calculation described Here.
Another Option would be to use Linq for calculation Multiply up Values from Array
class Program
{
    static void Main(string[] args)
    {
        int broj;

        List<int> produktBrojeva = new List<int>();

        do
        {
            Console.WriteLine("Unesite broj: ");
            int.TryParse(Console.ReadLine(), out broj);

            if (broj <= 0)
            {
                Console.WriteLine("Krivi unos.");
            }
            else
            {
                produktBrojeva.Add(broj);
            }
        } while (broj != 0);
        Console.WriteLine();

        //Initialize with 1
        int produkt = 1;

        for (int i = 0; i < produktBrojeva.Count; i++)
        {
            //Calculate Product
            produkt *= produktBrojeva[i];

            Console.WriteLine(produktBrojeva[i]);
        }

        //Write Product to Console
        Console.WriteLine($"Product {produkt}");
    }
}

