Phone Number
Source: Indonesia Mathematics Olympiad 2006 Day 2 Problem 6
June 2, 2008
geometryprobabilitycombinatorics proposedcombinatorics
Problem Statement
Every phone number in an area consists of eight digits and starts with digit . Mr Edy, who has just moved to the area, apply for a new phone number. What is the chance that Mr Edy gets a phone number which consists of at most five different digits?