In this lecture, we first spend some time to review the results of Lab 2 – a lab focused on the hand simulation of an inventory-management problem. That provides a discussion of statistical blocking and common random numbers and how they are related to paired t-tests. It also provides a brief motivation for Common Random Numbers (CRNs). Ultimately, we pivot back to talking about hand simulation in general and introduce how to use a spreadsheet to execute a discrete-event system simulation using relationships between entities (as opposed to manually executing state transitions at each simulated event).