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

Little Cat’s Feet

It comes in on little cat’s feet,
Is neither sour, nor sweet.
Hovers in the air,
And then is not there.

Fog or mist

Posted in Riddles

How Many Fs?

Read this sentence.

   Finished files are the re-
   sult of years of scientif-
   ic study combined with
   the experience of years.

How many times does the letter F appear?

Six times. Most people skip the word ‘of’ and only count three.

Posted in Brain Teasers

What Digit Does Each Letter Represent?

This is what you know:

1. Each letter represents a different digit from 1 to 9
2. The total of each row is 17.
3. (B × B) + B + F = A
4. C × F = EF (a 2-digit number, not their product)

A B C
D E F

What digit does each letter represent?

A = 7
B = 1
C = 9

D = 8
E = 4
F = 5

A + B + C = 17
D + E + F = 17
B2 + B + F = A
C × F = EF

To begin with, B has to be a 1 or 2 or else A wouldn’t be a single digit. Plug in B = 2, gives you 6 + F = A, meaning F and A can only be (1,7) or (3,9). To get 17, C would have to be 8 or 6, but those values don’t work for C × F = EF. So B must be 1.

2 + F = A means F and A can be (2,4), (3,5), (4,6), (5,7), (6,8) or (7,9). To get 17 on the top row, the only option that leaves C as a single digit is F = 5 and A = 7.

C × F = EF
9 × 5 = 45, so E = 4 and D = 8 to make the second row equal to 17.

Posted in Brain Teasers

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

White, Round Not Always Around

I’m white, I’m round, but not always around. Sometimes you see me, sometimes you don’t. What am I?

The moon.

Posted in Riddles

Longest Word in English

What is the longest word in the English dictionary?

Smiles because there is a mile between the two s’s.

Posted in Brain Teasers
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How Much Dirt?

How much dirt is there in a hole that measures two feet by three feet by four feet?

None. A hole doesn’t have any dirt.

Posted in Brain Teasers

What House Weighs The Least?

What type of house weighs the least?

A lighthouse.

Posted in Riddles

I Build Up Castles

I build up castles.
I tear down mountains.
I make some men blind,
I help others to see.
What am I?

Sand.

Posted in Riddles