Dr. Johnson’s File Numbering Algorithm

Introduction

Dr. Johnson employs a unique algorithm to number his files.

Current File Numbers

The numbers assigned to his first five files are as follows: 3, 8, 15, 24, and 35.

Can You Predict the Next Number?

What do you think is the number on his next file?

Answer

The next number is 48. The pattern is established by adding consecutive odd numbers:
– 3 + 5 = 8
– 8 + 7 = 15
– 15 + 9 = 24
– 24 + 11 = 35
– 35 + 13 = 48

The sequence can also be represented as (x + 5, +7, +9, +11, +13, …).