Twice the Sum of Its Digits

What number is twice the sum of it’s digits?

18.

1 + 8 = 9
2 × 9 = 18

Posted in Brain Teasers

$500 For Basketball

500 people attended a high school basketball game and raised $500 for the school.

The prices were as follows:
Mothers $3.00
Fathers: $2.00
Children $0.48

More mothers than fathers turned up. How many children were there?

375 children (70 mothers and 55 fathers)

Posted in Brain Teasers

Related Strangers

A man gets off the bus looking for an address and approaches a couple walking in the same direction for directions. The woman says they’re going that way and take him. Along the way the man asks if they’re related. The woman grins and says, “We’re not strangers. This man’s mother is my mother’s mother-in-law.” The man is confused but doesn’t say anything. When he gets back home he tells his wife about the conversation and she can’t figure it out either. They decide to ask their lawyer and he eventually works it out with pen and paper. How are the couple related?

The couple is either a man and his daughter or an uncle and his niece.

Posted in Brain Teasers

Wily Winifred and the Case of the Odd Numbers

Mrs. Shine was having a rough day and wanted a break. So she asked her class to calculate the sum of the first 50 odd numbers. In a few moments, Winifred was at her desk with the correct answer of 2,500. Stunned, Mrs. Shine figured she must have gotten lucky, and sent precocious Winifred back to her seat with the task of finding the sum of the first 75 odd numbers. Again, Winifred returned in seconds with the correct answer (5,625).

How did Winifred find the answer so quickly?

Winifred, being the precocious child she is, realized there was a pattern when computing smaller sums of odd numbers.

First 3: 1 + 3 + 5 = 9
First 4: 1 + 3 + 5 + 7 = 16
First 5: 1 + 3 + 5 + 7 + 9 = 25

Do you see the pattern like our dear friend Winnie?

For the first n odd numbers, the sum is equal to n2. Thus the first 50 is 502, or 2,500, and the first 75 is 752, or 5,625.

Posted in Brain Teasers

Eternally Joining In A Single Bite

With pointed fangs it sits in wait,
With piercing force it doles out fate,
Over bloodless victims proclaiming its might,
Eternally joining in a single bite

What is it?

A stapler.

Posted in Riddles

My Thunder, Lightning and Rain

My thunder comes before the lightning.
My lightning comes before the clouds.
My rain dries all the land it touches.

What am I?

A volcano.

(via Reddit)

Posted in Riddles
Tagged with

One Two Six Sequence

What is the next number in this series?

1, 2, 6, 42, 1806, ___

To get the next number, multiply the previous number in the series by itself plus one:

n × (n + 1).

For example, to get 6, multiply 2 × (2 + 1)
To get 42 multiply 6 × (6 + 1)

Thus, 1806 × 1807 = 3263442

Posted in Brain Teasers
Tagged with

Built From Anything You Don’t Like

I’m built from anything you don’t like,
You’re using me right now in fact,
I am one but represent many,
When attacked I’m easily cracked,
I’m created in seconds but live forever
And though you may not understand,
I’ll help you do well but be careful my friend,
Hurt me and you won’t withstand.

What am I?

Character (or characters).

Kids are often told, when dealing with unpleasant things, that it builds character. You’re reading the characters this riddle is written with. In computer science a char is often represented by one byte and can store any character you want.

When politicians have their character besmirched it can swiftly change the voting public’s mind about them. Characters in novels are created with a few lines but live on in our memories. And if your character or reputation is damaged, you may find it hard to deal with the aftermath.

And here’s a great quote from Warren Buffet on your character.

“It takes 20 years to build a reputation and five minutes to ruin it. If you think about that, you’ll do things differently.” — Warren Buffet

Posted in Riddles

Number Abbreviations

What do these represent?

24 = HiaD
26 = LotA
7 = DotW
9 = LoaC
12 = SotZ
88 = PK

24 hours in a day
26 letters of the alphabet
7 days of the week
9 lives of a cat
12 signs of the Zodiac
88 piano keys

Posted in Brain Teasers

Slice My Head

You use a knife to slice my head and weep beside me when I’m dead.

An onion.

Posted in Riddles