# Not a Burger

Today's mentalfloss.com Brain Game Think Thursday challenge is a throwback that we offered nearly five years ago. It's still a good one!

What's the next letter in this sequence?

K, M, G, T, P, ?

Here is the SOLUTION.

SOLUTION:

## E.

The letters represent "the first six entries in the International System of Units prefixes for unit multiples." But if you don't speak geek:

They stand for 1,000 times the previous unit of measurement.

base unit
K = kilo (1,000 units)
M = mega (1000K units)
G = giga (1000M units)
T = tera (1000G units)
P = peta (1000T units)... then our answer is:
E = exa (1000P units).

NOTE: In binary systems (like those used for computer memory), the multiple is 1024 instead of 1000, but the prefixes are the same. 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.