How many triangles are there in this image

Some editors saw four triangles. Others saw A few saw 6, 16, Even more saw Life has no meaning. We then posed the problem to our Instagram followers, whose replies also ran the gamut, from 5 to 14 to Turns out virtually all of the mathematicians I contacted found the same solution—but not all of them figured it out in the same way.

Hey, that was quick. Ready for the answer? The only way to form triangles in the figure I drew, Erikkson-Bisque says, is if the top vertex corner is part of the triangle. The base of the triangle will then have to be one of the three levels below.

This gives 18, or 3 times 6 triangles. Remember high school math? Johanna Mangahas, Ph. I could have made this much easier on readers—and, crucially, much easier on my inbox—had I just sketched the triangle on plain, white computer paper.

But no. I unfortunately drew this triangle on lined paper, and lots of smart people have correctly pointed out that, well, actually , if you count the light blue parallel lines in the image in addition to the dark blue lines written in marker, there are actually more than 18 total triangles here—considerably more.

I never specified to only use those dark blue lines, and thus, I am wrong. You are right. One reader, Ralph Linsangan, totally owned me by sending this image, in which he marks every additional triangle found under the technicality, flagging 17 additional triangles for a total of That kind of dedication is just one of many reasons I love Popular Mechanics readers.

Until the next teaser! Outstanding point , Poingly. Reader James Goodrich took it another step further, suggesting we open our minds to consider what a triangle could be:.

I did, James. Good Subscriber Account active since Shortcuts. Account icon An icon in the shape of a person's head and shoulders. It often indicates a user profile. Log out. US Markets Loading H M S In the news. Diana Bruk , Best Life. A new brain teaser seems to be stumping the internet. Journalist Jitesh Pillaai shared a drawing of several triangles hidden within one triangle and asked his followers to identify just how many they could find.

Answers were all over the place, and even those who are good at math seemed to be stumped. Sign up for notifications from Insider!