I already think that the user may have understood the answers. Because there are so many good programmer.. in simple wording % tells you the reminder after dividing with your own integer.
e.g.
int a = int.Parse(Console.ReadLine());
int b = a % 2;
Now your input 13, it will give 1, because after diving 13 by 2 remainder is 1 in simple mathematics. Hope you got that.