Casework

Casework is solving counting or probability problems by considering the different cases and adding them together. While casework is sometimes the most elegant method of solution, it may be considered brute force when a more elegant solution exists.

Video Introduction

This is a great video for learning the basics of casework, complementary counting, and overcounting: https://youtu.be/Zhsb5lv6jCI

Example Problems and Solutions

Introductory

• 2006 AMC 12A Problem 20

• 2005 AMC 10A Problem 14

Intermediate

• 2004 AIME 2 Problem 2
• 2004 AIME 2 Problem 4
• 2005 AIME 1 Problem 5
• 2000 AIME 1 Problem 5

See also

• Math books