Who ever working on Calculated columns, please follow these formulas for the calculated columns. You can find the information on Calculated columns formulas in the following Link.
http://office.microsoft.com/en-us/sharepointtechnology/HA101054791033.aspx?pid=CH100650061033
Using above URL, find the appropriate Formula.
Important : Before updating to the Sharepoint Calculated Column formulas, your list must be empty, otherwise it will not allow you to change the formula.