Array newbie needs help

First of all, hello. This is my first post and first time viewing these forums. I’m just starting out with Actionscript really, and I’m having a difficult time accomplishing what I’d like to do.

I’ll try to explain as best I can and post the little bit of code I have thusfar…

I have 118 instances of a particular a particular movie clip arranged in a specific manner. I’d like to have those instances play randomly once and only once each. Here’s what I have so far:

onClipEvent (enterFrame) {
	random_square = Math.floor(Math.random() * (120 -  1)) + 1;

(“square_mc” being the clip whose instances I want to play randomly)

The clips are playing randomly but repeating, obviously. I have no experience with arrays, and it occurred to me that I probably have to have at least some knowledge of arrays in order to accomplish what I want to do. Is there anyone out there that could help me out with this code (randomly play each instance only once)? I’d really appreciate it. Thanks.

P.S. I did use the search tool, but couldn’t find what I was looking for.