Inventory.) (a) Within 60 days after the issuance of his letters the representative of the estate of a decedent or ward shall file in the court a verified inventory of the real and personal estate which has come to his knowledge and of any cause of action on which he has a right to sue. If any real or personal estate comes to the knowledge of the representative after he has filed an inventory he shall file a supplemental inventory thereof within 60 days after it comes to his knowledge.
     (b) The inventory must describe the real estate and the improvements and encumbrances thereon, state the amount of money on hand and list all personal estate.