What's wrong with the puzzle in this video?

I didn't understand. Do you understand what happens?

(Click the image to open the video)

  • 2
    $\begingroup$ Just an optical illusion as the "squares" down the middle are not true squares. The sum of the areas of the 4 parts is still 64. $\endgroup$ Aug 9 '16 at 17:12

Obviously, $64\neq65$. Observe the diagram below:

enter image description here

The slopes of the diagonals of the blue and pink pieces are each $2/5 = 0.4$, whereas the slopes of the diagonals of the green and red pieces are each $3/8 = 0.375$. Thus, while the shapes made by the top two and bottom two pieces may look like triangles, they are in fact concave quadrilaterals, which creates a thin white space between the pieces. This white space has area $1$, so the area, as expected, stays constant at $64$.


Not the answer you're looking for? Browse other questions tagged or ask your own question.