Supporting performance objectives 47 and 52 of the V-TECS (Vocational-Technical Education Consortium of States) Secretarial Catalog, both a set of student materials and an instructor's manual on computing extensions and completing monthly statements from invoices are included in this packet. (The packet is the third in a set of nine on performing computational clerical activities--CE 016 951-959.) The student materials include information on computing extensions and completing monthly statements from invoices, a student activity, a check-out activity, and sample forms. The instructor's manual includes instructions for duplicating the sample forms, suggestions for administering the packet, and answer keys for the activities. The materials are designed for self-paced individual instruction and may be adapted for use with large groups. (A separate booklet--CE 016 911--lists contents for the nine packets in this set along with those in several other sets--seventy-eight packets in all--based on the same V-TECS catalog.) (JT)