Counting numbers with adjacent equal digits

Topic Classification: Tags:
Topics: combinatorics, enumeration Prerequisites:
Supplies: Pedagogy:
Grade Vs Difficulty:
  EasyModerateChallengingPerplexing
1-2
3-4
5-6
7-8
9-10
11-12
13-14
Problem

Find the number of integers from 0 to 999999 that have no two
equal neighboring digits in their decimal representation.

Details
Contributer: TRD
Authors
References
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