How to Add number to classname

How to Add number to classname

Hello, i am new for jQuery and i want to know when i use this code:

$(function() {
            $('ul li div').each(function (i) {
                $(this).addClass("col-" + (i + 1));
            });
        });

div can add class col-1, col-2, col-3 etc

<ul>
      <li>
            <div class="col-1">Menu</div>
            <div class="col-2">Menu</div>
            <div class="col-3">Menu</div>
      </li>

/* But next li tag div add classname col-4, but i don't want this, i want col-1, col-2, col-3 */
       <li>
            <div class="col-4">Menu</div>
            <div class="col-5">Menu</div>
            <div class="col-6">Menu</div>
      </li>
</ul>

I'm not good English sorry :)