Stripping $ from php values
<p>I have a form where users can enter the amount they spend on their phone bill and then I tell them how much they could save if they switched to vonage, skype etc.  </p>

<p>I pass the value "$monthlybill" in the url and then do some math to it.  The problem is that if the user writes "$5" instead of "5" in the form, it breaks and is not recognized as a number.  How do i strip out the dollar sign from a value?</p>
