[ruslan_mart]

<div id="checks">
<input type="checkbox" value="1000">
<input type="checkbox" value="100">
<input type="checkbox" value="10">
<input type="checkbox" value="1">
</div>

<script>
document.getElementById('checks').onclick = function()
{
    var chec = document.getElementById('checks').getElementsByTagName('input');
    var sum = 0;
    for(i=0;i<chec.length;i++)
    {
        if(chec[i].checked)
        {
            sum += (chec[i].value*1);
        }
    }
    alert(sum);
}
</script>