This document provides a lesson on simple interest, including definitions, formulas, and examples. It begins with an introduction to simple interest and the basic formula to calculate interest. It then provides examples of using the formula to find interest and maturity value for different loan scenarios. The document also distinguishes between ordinary interest and exact interest, providing the formulas and an example calculation for each. Finally, it demonstrates how to calculate actual time and approximate time for interest purposes and provides examples of interest calculations using both actual and approximate time periods. The overall document serves as a tutorial to teach students how to calculate simple interest for different loan scenarios.