Permutation and Combination,a topic in combinatorics, was introduced into the Singapore Additional Mathematics syllabus in 2002, in line with a greater emphasis on mathematical problem solving. Problems in combinatorics usually have different approaches of solving. Using one approach, a particular problem may be judged as not required for examination syllabus while from another approach the same problem may be seen as a non-routine problem that elicits pupils' higher order thinking skills. In this study, a survey was conducted on a group of 27 in-service teachers on their perception of eight problems on combinatorics. This paper presents the results of the survey. The conclusion based on this survey and their implications are discussed.