Exam timetabling is a tedious task faced in universities. We present a matheuristic to solve the exam timetabling problem related to the Toronto benchmark. We propose first a non-linear formulation used to find an initial feasible solution. We briefly describe a former linear formulation and introduce a new compact linear formulation. This compact formulation drastically reduces by 99% the numbers of variables and constraints. We propose a matheuristic based on both formulations to solve the problem. The approach achieves better results when compared to existing mathematical-programming-based heuristics.