Very simple question

I get the following error when the code below is compiled

Error    1    The left-hand side of an assignment must be a variable, property or indexer    C:\Users\numerical25\AppData\Local\Temporary Projects\ConsoleApplication1\Program.cs    16    22    ConsoleApplication1

Can someone tell me whats wrong

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i = 1; i < 40; i++)
            {


                if ((i % 10) = 0)
                {
                   
                }
            }
        }
    }
}