Fun Optical Illusions

[LevelUP]

It's weird, on the ipad mini 2, they all show as flipped upside down, until I reach the bottom 6.  On the laptop screen, they're all right side up, I don't see it at all start flipped upside down.  Cool, I'll test this out again, seems funny, it's just an interesting illusion!

I think the size of the image makes a difference.

For me, it's easier to see on my tablet, though for larger screens, I can see it more clearly if I adjust the zoom on the browser for a smaller size.