* is JavaScript for the multiplication sign.

my new one_row.js
function one_row(row) {
  var s1=" <img src='counters/0.png' class='cell' id='";
  var s2="' cn='0' onClick='cell_clicked(this);'>";
  var id=row * 5;
  for (var i=0; i<5; i++) {
    document.write(s1 + id + s2);
    id++;
  }
  var s1="<div id='s";
  var s2="'>0</div>";
  document.write(s1 + row + s2);
}

So when the player clicks a cell, cell_clicked can fetch the id like this:

  var id=image.id;

It can then figure out the row number using the parseInt function which will return the integer part of the result of the division.

  var row=parseInt(id/5);

It can then pass that row number to get_cns so it works on the clicked row.

  var arr=get_cns(row);

And, finally, it can put the score in the right place thus:

  var element=document.getElementById('s' + row);
  element.textContent=score;