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

Four Chains in One Loop

You have four chains. Each chain has three links in it. Although it is difficult to cut the links, you wish to make a single loop with all 12 links. What is the fewest number of cuts you must make to accomplish this task?

Three cuts. Cut each link in one chain. Separate them, and use the links to join the ends of the three intact chains.

Posted in Brain Teasers

Blame the Couple

A married couple is traveling by bus on dangerous mountain roads. Midway through their journey the bus stops for snacks and a restroom break. The couple is enjoying the postcards in the store when the bus driver curtly tells them it’s past time to leave. Fifteen minutes after, the bus is hit by a mud slide and two people are killed. The couple blames themselves for the deaths. Why?

They blame themselves because they caused the bus to be late. If they had been on time, the bus would have already passed the location of the mud slide.

Posted in Brain Teasers

A Promise to the President

Ronald has a rare opportunity to meet the President of the United States. During his visit the president gives him a gift but tells Ronald he is never to sell it unless he sees the president again. Ronald consents, but the president dies later that year. Years later a man offers to buy the President’s gift for $1000. Ronald agrees and exchanges the gift for 20 crisp $50 bills. Did he keep his promise?

Yes. The president was Ulysses S. Grant, who died in 1885 and whose face has been on the $50 bill since 1913. He saw the president on the bills before he made the exchange.

Posted in Brain Teasers

Wolves and Owls

You are in the woods with owls and wolves. There are 22 eyes and 32 legs. How many owls and wolves are there?

5 owls and 5 wolves, (not 6 owls because 2 of the eyes and legs are yours).

2 * owls + 2 * wolves = 20 eyes
2 * owls + 4 * wolves = 30 legs
owls + wolves = 10 eyes → owls = 10 – wolves
owls + 2 * wolves = 15 → 10 – wolves + 2 * wolves = 15 → wolves = 5
owls + 5 = 10 → owls = 5

Posted in Brain Teasers

The Camel Race

An Arab sheikh tells his two sons to race their camels to a distant city to see who will inherit his fortune. The one whose camel is slower will win. The brothers, after wandering aimlessly for days, ask a wise man for advise. After hearing the advice they jump on the camels and race as fast as they can to the city. What did the wise man say?

The wise man said to switch camels.

Each son owns a camel, let’s call them Camel A and Camel B. If Camel A is slower, son A gets the fortune. If Camel B is slower, son B gets the fortune. Neither of the sons want to enter the city first because they won’t get the fortune.

When they switch camels, son A is now riding his brother’s camel (camel B) and son B is riding his brother’s camel (camel A). Now, they each want the camel they’re riding to get to the city first. If son A wins the race on camel B, that means his camel, camel A, was slower and he wins the fortune. The same is true for the other way around if the second son wins the race on camel A.

Posted in Brain Teasers

Bricks to Finish a Building

How many bricks does it take to finish a brick building?

One (the last one is the only one that can finish the building).

Posted in Riddles

Frederick’s Epitaph

Frederick died after a long and productive life of 87 years, but this epitaph was written on his headstone:

Frederick lived a good long life,
He loved his children and his wife,

He was honest, kind and deserved nothing but praise,
Even if he only had twenty-one birthdays.

How is this possible?

He was born on February 29th in a leap year. Consequently, in his 87 years, he only witnessed twenty-one of his actual birthdays. The other years there was no February 29th.

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

Apples and Lies

During lunch hour a group of boys from Mr. Bryant’s homeroom visited a nearby grocery store. One of the five took an apple.

Jim said, “It was Hank or Tom”.
Hank said, “Neither Eddie nor I did it.”
Tom said, “Both of you are lying.”
Don said, “No, one of them is lying, the other is speaking the truth.”
Eddie said, “No, Don, that is not true.”
When Mr. Bryant was consulted, he said, “Three of these boys are always truthful but two will lie every time.”

Who took the apple?

Tom took the apple
Jim was telling the truth
Hank was telling the truth
Tom was lying
Don was lying
Eddie was telling the truth
(three telling the truth and two lying)

Posted in Brain Teasers