Need help modifying i++ count code.

I have this script that would show the <div> tags based on user selection from one select menu.

I want to change it so that it works i na new way.

I have 7 select menus. Stacked like this,
1.
2.
3.
4.
5.
6.
7.


I want this script to only add the next <div>
so it would only be adding +1

here's the old script

<script language="JavaScript">
function ShowMenu(num, menu, max)
{
//starting at one, loop through until the number chosen by the user
for(i = 1; i <= num; i++){
//add number onto end of menu
var menu2 = menu + i;
//change visibility to block, or 'visible'
document.getElementById(menu2).style.display = 'block';
}
}
</script>


see the line : for(i = 1; i <= num; i++){

Instead i want it so that when user makes a selection on Select menu 1, it will then show Select menu 2. when user makes a selection on Select menu 2, it will then show Select menu 3. etc .

How do i change that to add 1 , or as many as i want?

thank you