X-ray fluorescence is a non-destructive technique that allows elemental composition analysis. In this paper we describe a prescription to obtain the elemental composition of homogeneous coins, like 50 cent Euro coins, and how to get the quantitative proportions of each element with the help of Monte Carlo simulation. Undergraduate students can carry out both the laboratory work and the simulation, thus exploiting an analysis technique widely employed in contemporary physics. (Contains 4 tables and 5 figures.)