Geeks To Go is a helpful hub, where thousands of volunteer geeks quickly serve friendly answers and support. Check out the forums and get free advice from the experts. Register now to gain access to all of our features, it's FREE and only takes one minute. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more.
What do you mean by a formula, its measured in frequency, unless you are meaning one of the benchmark calculations of which there are many you would have to specific(you would be as well googling it). If you want the formula for frequency you can easily find that out.