Each of the triangular numbers that are below 1000 is written on a separate card. Some of these cards are then placed in a circle so that, viewed from the center, the right-hand digit of each card matches the left-hand digit of the card to its right. No tricks are used such as turning a card upside-down.

What's the maximum number of digits that can appear on such a subset of the cards?

Oh! Oh!  This wording is very significant, "the right-hand digit of each card matches the left-hand digit"!

And I see Dej Mar has taken this into account in his explanation.

Edited on January 12, 2008, 2:02 am

Posted by brianjn on 2008-01-12 01:58:25