Bijection principle is a very useful tool for combinatorics. Here we pick up a problem that appeared in I.S.I.’s B.Stat-B.Math Entrance.

# Part 1: The problem and the hints

## Part 2

## Part 3

Bijection principle is a very useful tool for combinatorics. Here we pick up a problem that appeared in I.S.I.’s B.Stat-B.Math Entrance.

Can you teach me the Bijection principle?

Bijection principle is taught Cheenta Early Bird Math Olympiad program

Is there any book or PDF file where I can read it?

Yes. You may consult books like Principle and Techniques of Combinatorics or Excursion in Mathematics