In this lecture, we describe how simple computational tools such as spreadsheets can be be used not only for Discrete Event System simulation but also for Monte Carlo simulation. This provides an opportunity to describe different classes of inventory problems (newsvendor, order-up-to, etc.) that we may see again in later lectures. Ultimately, we describe how although spreadsheets can be very powerful, they are not practical to use for simulation with complex systems that may need to be reconfigured during the analysis and design process. Thus, we really use tools like spreadsheets for analysis of data from simulations which are implemented within other tools and frameworks.