A figurate number stack is built using only the digits 0 through 9 exactly once.

Each tier is a figurate number of the order labelled; no number has a leading zero.


How many solutions can you offer?

I initially made the assumption as it appears that Charlie had, that a unit in the given puzzle is to be defined as any integer. Yet, the only mathematical definition I found gives the units (of the set of Real numbers) as -1 and 1. 
As we are dealing with digits 0 to 9, with no negative numbers, the top tier, unit, by this found definition, should then be 1. This leaves only the solution:

UNIT    :    A    =    1 
TRIANGLE:   B C   =   7 8 
SQUARE  :  D E F  =  3 2 4
PENTAGON: G H I J = 9 5 6 0

Posted by Dej Mar on 2008-12-17 11:38:49