failoflife,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
<script>
$(function(){
var i = $("[name=table]"), t = $(".myTable");
$("#addcol").click(function() {
var table = t.eq(i.index(i.filter(":checked")));
$("tr", table).append(function(i) {
var num = "a" + (i + 1) + "," + ($("td", this).length + 1);
return $("<td>").append($("<input/>", {
attr: {
size: "2",
maxlength: "2",
placeholder: num
}
}))
})
});
})
</script>
</head>
<body>
<table class="myTable">
<tr>
<td><input type="text"></td>
<td><input type="text"></td>
</tr>
<tr>
<td><input type="text"></td>
<td><input type="text"></td>
</tr>
</table>
<table class="myTable">
<hr>
<tr>
<td><input type="text"></td>
<td><input type="text"></td>
</tr>
<tr>
<td><input type="text"></td>
<td><input type="text"></td>
</tr>
</table>
<hr>
<table class="myTable">
<tr>
<td><input type="text"></td>
<td><input type="text"></td>
</tr>
<tr>
<td><input type="text"></td>
<td><input type="text"></td>
</tr>
</table>
<table class="myTable">
<hr>
<tr>
<td><input type="text"></td>
<td><input type="text"></td>
</tr>
<tr>
<td><input type="text"></td>
<td><input type="text"></td>
</tr>
</table>
<input type="radio" name="table" checked>Таблица 1
<input type="radio" name="table">Таблица 2
<input type="radio" name="table">Таблица 3
<input type="radio" name="table">Таблица 4
<input id="addcol" type="button" value="Add Column" />
</body>
</html>