Seemingly Simple Math

What is the answer to this math problem:

8 ÷ 2 (2 + 2)

16 or 1, depending.

According to PEMDAS, parentheses come first: 8 ÷ 2 (4)

Then, even though multiplication is first in PEMDAS, you go left to right: 4 (4) = 16

If you got 1, you’re in good company. That’s what I got at first too but most calculators I’ve tried get 16.

I found this at Popular Mechanics and the debate continues online.

Posted in Brain Teasers

I Live in Water

I live in water
If you cut my head I’m at your door,
If you cut my tail I’m fruit,
If you cut both I’m with you

What am I?

A pearl. They’re found underwater. Removing the head (p) leaves Earl, a guy who could be at your door. Removing the tail (l) leaves pear, a fruit and if you cut both off you’re left with ear, which is with you because it’s attached to your head.

Posted in Riddles

I Change Stature As I Age

I change stature as I age, but my importance does not differ by age. My importance is manifested mostly when with my boss. When we part, I am of no importance.

What am I?

A pencil. It gets shorter with use, but is no less important. Its impact is from the person using the pencil to write or draw. Without them, the pencil is just an idle tool.

Thanks Keller!

Posted in Riddles
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Liquid In Nature

I am liquid in nature,
But don’t bend me to far,
For then I may break
And give you a scar.

What am I?

Glass. Technically, glass is an amorphous solid, but that doesn’t have the same ring to it.

Posted in Riddles
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Divisible By One To Ten

What is the smallest number that is evenly divisible by 1 through 10?

2520.

2520/1 = 2520
2520/2 = 1260
2520/3 = 840
2520/4 = 630
2520/5 = 504
2520/6 = 420
2520/7 = 360
2520/8 = 315
2520/9 = 280
2520/10 = 252

Posted in Brain Teasers

Same Forward, Backward and Upside Down

What word is the same written forward, backward and upside down?

NOON. The word needs to be a palindrome and made up of only these letters that look the same upside down:

H I N O S X Z

For instance, SOON doesn’t work, because even though each letter looks the same upside down, it reads NOOS.

Posted in Riddles

The Ages of a Prince and Princess

A princess is as old as the prince will be when the princess is twice the age that the prince was when the princess’s age was half the sum of their present ages.

What are their ages?

This one took a while to figure out and there are numerous valid ways of finding the answer.

Here is the solution I came up with

I created the following table from the riddle:

 CurrentFuturePast
Princessx2z(x+y)/2
Princeyxz

I then created three equations, since the difference in their age will always be the same.
d = the difference in ages
x – y = d
2z – x = d
x/2 + y/2 – z = d

I then created a matrix and solved it using row reduction.

xyz
1-10d
-102d
.5.5-1d

It reduced to:

xyz
1004d
0103d
0015d/2

This means that you can pick any difference you want (an even one presumably because you want integer ages).
Princess age: 4d
Prince age: 3d

Ages that work

PrincessPrince
43
86
1612
2418
3224
4030
4836
5642
6448
7254
8060

To see other solutions check out the comments from when I posted this on my blog.

Posted in Brain Teasers

Toss Me Out the Window

Toss me out of the window,
You’ll find a grieving wife,
Pull me back but through the door, and
Watch someone give life!

What am I?

The letter “n”. (widow, donor).

Posted in Riddles

I’m Located In the Middle of Nowhere

I am located in the middle of nowhere. What am I?

The letter ‘h’. It is the middle letter of the word ‘nowhere’

Posted in Riddles

I Used to Be The Light of Your Life

I used to be the light of your life,
I’d keep you warm while I cried,
Now I’m forgotten and tossed away.

What am I?

A candle. They used to be a primary source of light, and to a lesser extent heat. The “crying” is the wax rolling down the candle.

Posted in Riddles
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