Exam CTAL-TA topic 3 question 8 discussion

While identifying scenario’s for the use case "copy A4 – A4" for a new copier, the following scenario’s were identified:
Basic scenario: single side to single side
Deviations: single side to double side, copy of a set, copy using the automatic document feeder
Failures: no paper in paper tray, paper jam, out of staples
During interviews with both development and end-users it has been established that the failure scenarios can occur during the basic scenario and during each of the deviations.
How many test cases will be needed to achieve full coverage both for valid and invalid situations?