How old is Jennette Mccurdy and do you now how old Robbie Williams is?

How old is sam in real you now sam from icarly!if you now how old Jennette Mccurdy is then pleas tell me!I think she is 13 or 14 or 15!o and how old is Robbie williams i am a big fan of him you to?I think he is 41 or 40 or 39