# Geometry buffs: Pls explain this "How many triangles" puzzle **URL:** \ **Category:** Factual Questions\ **Created:** [December 10, 2021, 10:09pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860 "2021-12-10T22:09:48Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [December 10, 2021, 10:09pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/1 "2021-12-10T22:09:48Z")
I keep seeing this pop up on my FB feed. To me, I only see 4. But the answers in the comments are all over the place. So what am I missing here? > **[Can You Guess How Many Triangles Are in This Viral Photo?](https://www.businessinsider.com/can-you-guess-how-many-triangles-are-in-this-photo-2018-4)** > > Journalist Jitesh Pillaai shared a black-and-white drawing of several triangles hidden within one triangle and asked social media users to identify just how many of them they could find. It's driving everyone crazy! ---
**Author:** ![Aspidistra](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspidistra/32/3894_2.png) [@Aspidistra](https://boards.straightdope.com/u/Aspidistra)\ **Post date:** [December 10, 2021, 10:13pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/2 "2021-12-10T22:13:53Z")
I think it’s 18. Taking just the area from the top parallel line upwards, there’s a left triangle, a middle triangle, a right triangle, a double size left (ie taking the leftmost vertical-ish line as the left of it, and the line two across from that to be the right of it), a double-size right, and a triple-size (whole top row). That’s six already. Repeat again using the other two horizontal lines as the base in turn ---
**Author:** ![glee](https://avatars.discourse-cdn.com/v4/letter/g/b5a626/32.png) [@glee](https://boards.straightdope.com/u/glee)\ **Post date:** [December 10, 2021, 10:14pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/3 "2021-12-10T22:14:14Z")
I see 12. (hopeful!) Four between the top point and the first horizontal line. Another four between the top point and the second horizontal line. Another four between the top point and the bottom line. ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [December 10, 2021, 10:15pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/4 "2021-12-10T22:15:02Z")
I count 18. The top 3rd of the drawing contains 6. Three individual ones, one made out of the first two segments, another made out of the second two segments, and another made out of all 3. Extend down another 3rd and you get 6 more doing the same thing. Another 6 with the last 3rd. ---
**Author:** ![glee](https://avatars.discourse-cdn.com/v4/letter/g/b5a626/32.png) [@glee](https://boards.straightdope.com/u/glee)\ **Post date:** [December 10, 2021, 10:15pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/5 "2021-12-10T22:15:32Z")
Dang! What Aspidistra said. 😀 ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 10, 2021, 10:15pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/6 "2021-12-10T22:15:55Z")
I’m really curious how you’re seeing four, because any count that includes four would include others akin to those four. ---
**Author:** ![Aspidistra](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspidistra/32/3894_2.png) [@Aspidistra](https://boards.straightdope.com/u/Aspidistra)\ **Post date:** [December 10, 2021, 10:16pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/7 "2021-12-10T22:16:19Z")
where’s our ninja emoji?? ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [December 10, 2021, 10:17pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/8 "2021-12-10T22:17:17Z")
21 before I quit counting. Hint: triangles that appear to overlap other triangles are still triangles. ---
**Author:** ![Atamasama](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/atamasama/32/12961_2.png) [@Atamasama](https://boards.straightdope.com/u/Atamasama)\ **Post date:** [December 10, 2021, 10:20pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/9 "2021-12-10T22:20:05Z")
I also got 18. ETA: I finally read the article which confirms that it’s 18. ---
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [December 10, 2021, 10:20pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/10 "2021-12-10T22:20:21Z")
Yeah, I was counting the three obvious ones on top, then the one big one. I’m looking at it differently now after reading the previous comments in this thread. ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [December 10, 2021, 10:46pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/11 "2021-12-10T22:46:28Z")
18 for me. Curious about the 3 that got **gnoitall** to 21. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [December 10, 2021, 10:51pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/12 "2021-12-10T22:51:14Z")
18 for me ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [December 10, 2021, 10:51pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/13 "2021-12-10T22:51:14Z")
I object to the word “guess” in the headline. ---
**Author:** ![Horatius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/horatius/32/3572_2.png) [@Horatius](https://boards.straightdope.com/u/Horatius)\ **Post date:** [December 10, 2021, 10:55pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/14 "2021-12-10T22:55:09Z")
> [@Hampshire](#): > > I count 18. The top 3rd of the drawing contains 6. Three individual ones, one made out of the first two segments, another made out of the second two segments, and another made out of all 3. Extend down another 3rd and you get 6 more doing the same thing. Another 6 with the last 3rd. 19, because the overall outline is also a triangle. ---
**Author:** ![Atamasama](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/atamasama/32/12961_2.png) [@Atamasama](https://boards.straightdope.com/u/Atamasama)\ **Post date:** [December 10, 2021, 11:07pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/15 "2021-12-10T23:07:33Z")
> [@Horatius](#): > > 19, because the overall outline is also a triangle. You’re counting it twice. ---
**Author:** ![Riemann](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/riemann/32/3133_2.png) [@Riemann](https://boards.straightdope.com/u/Riemann)\ **Post date:** [December 10, 2021, 11:10pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/16 "2021-12-10T23:10:43Z")
I think @Grrr’s answer is correct, because he is the only one who followed the instruction to _guess_ how many triangles. All the rest of you are _counting_. ---
**Author:** ![Grrr](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/grrr/32/146_2.png) [@Grrr](https://boards.straightdope.com/u/Grrr)\ **Post date:** [December 10, 2021, 11:11pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/17 "2021-12-10T23:11:52Z")
LOL. 😃 ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [December 10, 2021, 11:12pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/18 "2021-12-10T23:12:03Z")
Took me a few tries, but I get 18 also. ---
**Author:** ![lobotomyboy63](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lobotomyboy63/32/2900_2.png) [@lobotomyboy63](https://boards.straightdope.com/u/lobotomyboy63)\ **Post date:** [December 10, 2021, 11:12pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/19 "2021-12-10T23:12:03Z")
I get 21. Consider the top horizontal “bar.” You can count three individual ones above it. You can combine the left and center…the center and the right…and all three combined. So I get six on that level. Drop two the next horizontal…by extension you have six more. And at the bottom, six more. That’s 18 total. But look at the center. You can make two more there. And one for the overall. That’s 21. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [December 10, 2021, 11:12pm UTC](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860/20 "2021-12-10T23:12:20Z")
The answer is 24. [Next page](https://boards.straightdope.com/t/geometry-buffs-pls-explain-this-how-many-triangles-puzzle/955860.md?page=2)