Sunday Times Teaser 2793 – Sum Triangles
by Victor Bryant
Published: 3 April 2016 (link)
The number of upwardly-pointing triangles (of all sizes) visible in this picture is ten. Trix has drawn a similar arrangement but with lots more rows: the number of small upward-pointing triangles in her bottom row is equal to her age and the total of upward-pointing triangles that can be seen is divisible by any of the digits 1 to 9.
How old is Trix?