You can go to sap webpage of SAP MM certification to get complete detail on SAP MM certification.
Please refer given link to refer sample questions on SAP MM certification exam.
Top of the all answers, self study, well understanding and indepth process steps of MM is important for certification.
Secondly, if you want to get few hints about sample questions and answers, you can search on net and you will find lot.
The best ever website which you can gain MM questions is :
This is the best.. do the test again and again until you get the correct answers. Correct not in the sense puzzling with answers again and again, understand the fundamentals of question and answers.