Triangular Number Order
Ten
is a triangular number, because 10 objects can be neatly arranged in an
equilateral triangle.
In
general, a triangular number is a number that can be represented as a triangle
with one object in the first row and each subsequent row contains one more
element than the previous row. (From the picture above, you might notice that
1, 3, and 6 are also triangular numbers.)
Order
the digits 1 through 9 so that the sum of any two adjacent numbers is a triangular
number.
This brainteaser was
written by Derrick Niederman.
