This lecture covers the statistical interpretation of entropy and disorder, focusing on calculating the multiplicity of micro-states in different configurations. Starting with the concept of irreversible adiabatic processes, the lecture delves into determining the number of micro-states in various scenarios. Through examples involving water bottles and books, the instructor explains the calculation of multiplicity and the significance of different configurations. The lecture progresses to discuss the general formula for multiplicity and the considerations for avoiding double counting. By exploring the distribution of particles and the selection of objects, the lecture illustrates how to calculate the total number of possibilities and determine the most probable configurations.