2013 UNCO Math Contest II Problems/Problem 8
Problem
EXAMPLE: The non-terminating periodic decimal 
has period three and is abbreviated by placing a bar over the shortest repeating block.
(a) If all digits 
through 
are allowed, how many distinct periodic decimals 
have period exactly six? Do not include patterns like 
and 
that have shorter periods.
(b) If only digits and 
are allowed, how many distinct periodic decimals 
have period exactly 
?
