# Ordinal People

Here's today's mentalfloss.com "Throwback" Think Thursday Brain Game, from about four years ago:

Cardinal numbers are counting numbers; 1, 2, 3, and so on. Ordinal numbers, on the other hand, represent an order; 1st, 2nd, 3rd, etc. With this in mind, here's today's Brain Game. And a word of caution: if you answer too quickly, you'll probably answer incorrectly! Good luck:

Counting all ordinal numbers from 1st to 100th,
how many of them end with the suffix "th"?

73 of them.

The unusual total is the result of the extra "th" entries 11th, 12th, and 13th.

4th through 20th = 17
24th through 30th = 7
34th through 40th = 7
44th through 50th = 7
54th through 60th = 7
64th through 70th = 7
74th through 80th = 7
84th through 90th = 7
94th through 100th = 7

Thanks for playing! Tomorrow, it's Free-for-All Friday!

iStock
What Is the Car's Parking Spot Number?
iStock

Today's brain teaser asks a simple question: in what numbered space is this car parked? This puzzle has been floating around the internet for a while, often attributed to a Hong Kong admissions test for first graders, which sounds quite difficult and may not be true. The Guardian traced it to legendary puzzle author David Bodycombe.

Give it a minute. The answer is below. And while you think it over, here are a couple amazing facts, courtesy of our Instagram account:

All right, did you get it? There's really no math involved besides simple counting. The key is to flip your screen upside down. Here, let us do the flipping:

What goes in the empty box? (Hint: It's not six.)

[h/t Insider/MSN]

Pop Quiz: See How Well Your Brain Handles the Stroop Test

Our brains are amazing organs. They’re capable of solving highly complex problems and achieving incredible feats. But the brain isn’t perfect. Despite its many strengths, it doesn’t take much to completely confuse it. Case in point: The Stroop effect.

The Stroop effect—named after John Ridley Stroop, who first wrote about it in a psychology paper—illustrates what happens when the brain is trying to process conflicting streams of information. Specifically, the test that produces the effect involves naming the color a word is printed in when the word itself is the name of a different color. (Example: seeing the word “red” in a blue font and saying “blue.") Reading words is easy, naming colors on their own is a bit harder—and when those two things conflict, the brain is sent into a bit of a tizzy.

You can watch the folks over at Science World in British Columbia above as they take the Stroop test, and play along to test your own mental flexibility. Be prepared to feel flustered.

For more about the Stroop effect, head over to Science World’s website.