2007 UNCO Math Contest II Problems/Problem 10

Problem

A quaternary “number” is an arrangement of digits, each of which is $0, 1, 2, 3.$ Some examples: $001, 3220, 022113.$

(a) How many $6$ -digit quaternary numbers are there in which each of $0, 1$ appear at least once?

(b) How many $n$ -digit quaternary numbers are there in which each of $0, 1, 2,$ appear at least once? Test your answer with $n=3.$

(c) Generalize.

This problem needs a solution. If you have a solution for it, please help us out by adding it.

2007 UNCO Math Contest II (Problems • Answer Key • Resources)
Preceded by Problem 9	Followed by Last question
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10
All UNCO Math Contest Problems and Solutions