London's immersive experience dedicated to visual perception and cognitive illusions – has introduced a brand-new brain teaser that's leaving people all over the UK utterly baffled. This freshly ...

We spent forever arguing about the brain teaser that asks: How many triangles do you see? Here, mathematicians reveal the real answer. See if you’re right.

According to Business Insider's quant reporter Andy Kiersz, the key to solving the problem is the height of the pink triangle. The area of a triangle is 1/2 (base x height).

But we know that the little triangle's height plus the pink triangle's height is 1, so that means the pink triangle's height is 2/3. Plug that on in and we get our area = 1/2 x base x height = 1/2 ...

That’s why it’s said that only someone with high IQ and excellent problem-solving skills can guess the correct number of triangles. Why optical illusions are good for your brain ...

Save guides, add subjects and pick up where you left off with your BBC account. Problem 5 is all about triangles and figuring out how they fit together. Maths teacher Chris Smith and pupils from ...