Enigma 1300: Numeros triangulares
20 August 2014
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From New Scientist #2458, 31st July 2004
This puzzle has appeared as an Enigma puzzle in both English and French versions, but incredibly it also works in Portuguese.
Triangular numbers are those that fit the formula n×(n+1)/2, like 1, 3, 6 and 10. In the following statement digits have been consistently replaced by capital letters, different letters being used for different digits: UM, TRES, SEIS, DEZ are all triangular numbers, none of which starts with a zero.
Which numbers are represented (in this order) by UM, TRES, SEIS, and DEZ?
Note: I am waiting for a phone line to be connected at my new house, so I only have sporadic access to the internet at the moment.