This is a problem-based lesson and activity where students discover a more efficient strategy for calculating compound interest and apply their knowledge of logs to solve compound interest problems. Throughout this 5-day lesson/activity, students solve a problem about saving money to purchase an iPad. They then use that problem, a mini-lesson, and practice problems to reinforce skills needed for the culminating task and write-up. The culminating task requires students to calculate the amount of money they must place in a savings account at a bank of their choice to save enough money to purchase an item of choice by a given date. The write-up provides an opportunity for students to explain their understanding of logarithms and their applications.