Five Hundred Begins It

Five hundred begins it, five hundred ends it,
Five in the middle is seen;
First of all figures, the first of all letters,
Take up their stations between.
Join all together, and then you will bring
Before you the name of an eminent king.

DAVID (Roman numerals).

Posted in Riddles

Throw It Out To Use

What do you throw out to use and take in when you’re done?

An anchor.

Posted in Riddles

A Great Woman

The first two letters of this English word refer to a male, the first three refer to a female, the first four to a great man and the whole word is a great woman.

What is the word?

Heroine (he, her, hero)

Posted in Riddles

Fifty Quarters

You have fifty quarters on the table in front of you. You are blindfolded and cannot discern whether a coin is heads up or tails up by feeling it. You are told that x coins are heads up, where 0 < x < 50. You are asked to separate the coins into two piles in such a way that the number of heads up coins in both piles is the same at the end. You may flip any coin over as many times as you want.

How can you do it?

Take x coins, flip all of them and put them in one pile. The rest of the coins form the second pile.

Posted in Brain Teasers

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

Kevin’s School Supplies

Kevin brings his school supplies to the counter. The cashier rings up his purchase for a total of $1.70. Kevin is puzzled, and says, “I bought 2 pencils at 2 cents each, 5 pencils at 4 cents each and 8 notebooks and 12 sheets of colored paper. I don’t remember the prices of the latter two, but the total can’t be $1.70.”

How did Kevin know?

Because 4 cents, 20 cents, 8 notebooks and 12 sheets of colored paper are all divisible by 4, but 170 cents isn’t.

Posted in Brain Teasers

Mysterious Math

This problem can be solved by preschool children in five to ten minutes, by programmers in an hour and by people with higher education…well, check it yourself.

8809 = 6
7111 = 0
2172 = 0
6666 = 4
1111 = 0
3213 = 0
7662 = 2
9313 = 1
0000 = 4
2222 = 0
3333 = 0
5555 = 0
8193 = 3
8096 = 5
1012 = 1
7777 = 0
9999 = 4
7756 = 1
6855 = 3
9881 = 5
5531 = 0
2581 = ?

What is the missing number and why?

Two. The number is how many closed circles there are in the 4 digits. 0, 6 and 9 each have one, 8 has 2.

Posted in Brain Teasers

Fix This Roman Numeral Equation

This Roman numeral equation is wrong, but you can fix it without changing any of the elements of the equation. How is this possible?

I + XI = X

Look at it upside down. Instead of changing the equation, you can change your perspective.

This is from Dan Brown’s novel, Origin.

Posted in Brain Teasers

The More You Run

The more you run, the harder I am to catch. What am I?

Your breath.

Posted in Riddles

Pushing Car Past Hotel Lands You in Jail

A man pushes his car by a hotel and gets sent to jail. Why?

The man is playing monopoly, and landed on the Go To Jail space. An alternative version of this is, “A man stops his car in front of a hotel and immediately knows he is bankrupt.” The answer is the same, that he’s playing Monopoly, but this time he landed on a space with a hotel and didn’t have enough money to pay the bill.

Posted in Brain Teasers