December 29, 2015 9:00 am

# Puzzles that left us scratching our heads in 2015

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Remember the strife over that dreaded blue (or was it white?) dress? How about the Singapore logic question for 14-year-olds that made you feel like you didn’t understand the world anymore? Here is a look back at some of the most fun — and frustrating — puzzles of the year.

### Blue dress

Is it white and gold or blue and black?

A debate over the colour of a dress was undoubtedly the most talked-about puzzle of the year.

It all started with a post by the user Swiked on a Tumbler account (the original post has been removed). The image was of a dress and the caption, “guys please help me – is this dress white and gold, or blue and black? Me and my friends can’t agree and we are freaking the f*** out.”

While some people saw white and gold, others saw blue and black.

WATCH: Why some people can see the true colours of the dress

READ MORE: Here’s why no one can agree on the colour of the dress

It turns out that the dress was indeed blue and black.

### When exactly was Cheryl’s birthday? The Singapore high school logic puzzle

If you like logic puzzles, this one was for you.

The question was part the Singapore and Asian Schools Math Olympiad test, given to some of the best students in the country (they would be equivalent to Grade 10 in Canada).

Here’s the question, posted on Facebook.

It gives you limited information and seems almost impossible. But there was a way to figure it out.

READ MORE: When is Cheryl’s birthday? How to figure out the Singapore math problem confusing the Internet

### Cat going up or down

Another optical illusion had the internet divided.

A photograph of a cat mid-stride on some stairs was posted to 9Gag.com asking “Is this cat going up or down?”

That set off a firestorm of replies with people insisting the cat was going up the stairs, while others insisting that it was “obvious” that the cat was going down.

The answer? It was never given.

### Underwater or jumping in?

A photograph of a little girl enjoying a splash in a pool stirred up another debate: was she splashing in water or underwater?

The photograph was posted to Reddit in September with people arguing over which it was.

WATCH: Jumping in or underwater? Another optical illusion baffles online photo sleuths

Though the girl’s hair isn’t wet, the bubbles of water and the filters used in the photo — along with the young girl’s scrunched up face — create the illusion that she is holding her breath under water.

–with files from Global’s Nicole Bogart, James Armstrong, Adam Frisk and Jenny Sung