How many triangles do you see in this image? | November 24, 2025

You thought you had the right answer, and yet… this famous puzzle is puzzling to even the most experienced eye! At first glance, you count a few triangles, then add them up as you progress through the “levels.” Simple? Not quite. The figure—a large triangle divided by three parallel lines at the base—hides more shapes than you can imagine. Ready to outsmart the trick and shine at your next quiz night? Follow the guide.

The Hidden Triangle Trap

Our brain loves to identify the most obvious small triangles and… forget the larger ones, formed by combining multiple areas. The result: we underestimate. In the classic configuration (4 rows formed by 3 lines parallel to the base), the correct answer is 27.  If
you got 26, you most likely missed a large compound triangle, often a triangle with the tip pointing upwards that extends over 3 levels, or a triangle “half-wide” on one side.

Step-by-step method: counting without mistakes

Identify the “upward” triangles by their height:

  • Level height 1:10
  • Height 2 levels: 6
  • Height 3 levels: 3
  • Height 4 levels: 1

Subtotal “up”: 10 + 6 + 3 + 1 = 20.

Add the “downward-facing” triangles resulting from the nesting of the segments: 7.

Total: 20 + 7 = 27.
Memory tip: think “20 ​​on top + 7 on the bottom” and you will avoid the classic forgetfulness.

see the continuation on the next page