As discussed in the previous post, when you add your mobile number to verify your account, you wouldn't think that the new number will be broadcast to everyone.
If you have done this, and you now realise that everyone on facebook (depending on your privacy settings) has been alerted about your "new numebr", there IS something you can do about it .. and it is retrospective (meaning that your change will make it as if you never accidentally published your number.
Go to your facebook settings (top right corner) and under PRIVACY, change your privacy level for your mobile number. But wouldn't this mean that people who are already alerted will still know my number? no, actually facebook status updates happen in that when you log on, whatever updates are currently available to you will be shown on your status updates. So if someone who was alerted to your new number logged in AFTER you changed your privacy settings, they won't see your number. The broadcasting of your mobile number will be removed from everyone's storyline or status updates and it will be as if you never made the update of your mobile number. It works, you can test this by getting a friend to check your account as you make the changes.