In one of the years, students were asked a question on **periodic functions** which were not exactly covered in the syllabus. But information given were sufficiently clear to allow us to figure out how to work out the sum. I have always advise my students to expect the unexpected and be flexible during examinations.

One of my students ask me on how to approach the question using a shorter method. In this post, I share with you one way you can analyse this question.