Tom, Dick and Harry were searching for 3-digit triangular numbers (numbers of the form k*(k+1)/2) that are themselves each the product of three different triangular numbers greater than 1 (so 1*3*15 = 45 doesn't count, nor does 3*10*10 = 300 because of the duplicated 10).

Each of them found a different triangular number. One of the triangular factors is found only in Harry's solution. Another of the triangular factors is found only in Tom's solution.

What are the three triangular factors making up Dick's solution?

This riddle was originally published in NewScientist, 17 March 2007.

Posted by Robby Goetschalckx on 2007-04-21 16:23:02