Numbers Map

Arrange the numbers from 1 to 8 in the following sequence.

     a
  b  c  d
  e  f  g
     h

Each number must not be diagonally or directly adjacent to any number directly before or after it.

For example, 2 can only be placed in one spot.

     2
  x  x  x
  x  1  x
     x

Here are two solutions (there might be more).

    7
3   1   4
5   8   6
    2

    2
5   8   6
3   1   4
    7
Posted in Brain Teasers

How Old is Malcolm, His Dad and Grandfather?

Malcolm is the number of weeks of his father’s age treated as days and his grandfather’s age in months. All three of their ages add up to 120 years. How old is Malcolm, his father and his grandfather?

Malcolm is 6.
The father is 42. 42 days = 6 weeks.
The grandfather is 72. 72 months = 6 years.

Posted in Brain Teasers

Leaves That Don’t Fall

I have wood but no bark,
And leaves that don’t fall,
I am made up of branches,
and come in sizes of all.

I am completely devoured many times,
over and over by a worm of a kind.
If you want to know the answer of mine,
look for the secret that I’ve stored inside.

What am I?

A library or bookstore.

Posted in Riddles
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One Way I’m Feeling Normal

One way I’m feeling normal,
Another I’m extremely thin,
I could be a punishment,
Or the type who always wins.

I’m free from all impurity,
And you may have divined,
I have a keen edge,
But of course I am refined.

Fine.

The riddle refers to a variety of meanings of the word fine.

Feeling normal refers to when you feel fine.
Extremely thin refers to a fine thread.
A punishment refers to being charged a fee.
The one who wins refers to an athlete who is physically trained and hardened close to the limit of efficiency.
Free from impurity refers to measuring the fineness of precious metals.
A keen edge refers to a knife with a fine edge.
Refined refers to fine manners or elegance.

Posted in Riddles

The Japanese IQ Test

Supposedly this is given as a test in Japan. I have no idea if that’s accurate.

There are 8 people who have to cross the river on a raft.

1. Policeman
2. Thief
3. Father
4. Boy 1
5. Boy 2
6. Mother
7. Girl 1
8. Girl 2

The rules are:

Only two people can cross at a time.
Only the adults can operate the raft.
The father can’t be with the girls unless the mother is there.
The mother can’t be with the boys unless the father is there.
The thief can’t remain with anyone unless the policeman is present.

How do you get them all across?

Instead of working it out by hand, here’s a flash version.

Click on the circle to start. Click on a person to put them on the raft and click on the lever to make the raft cross.

Here’s how I did it in 17 steps. Can you do it faster? Let me know in the comments.

1. Policeman (P)
2. Thief (T)
3. Father (F)
4. Boy 1 (B1)
5. Boy 2 (B2)
6. Mother (M)
7. Girl 1 (G1)
8. Girl 2 (G2)

1. P, T →
2. ← P

3. P, B1 →
4. ← P T

5. F, B2 →
6. ← F

7. F, M →
8. ← M

9. P, T →
10. ← F

11. M, F →
12. ← M

13. M, G1 →
14. ← P T

15. P, G2 →
16. ← P

17. P, T →

Posted in Brain Teasers

A Long Bicycle Ride

Hester goes out for an afternoon bicycle ride. She rides for one hour at five miles an hour, then three hours at four miles an hour and finally two hours at seven miles an hour. How many miles did she ride in total?

31 miles.

1 hour at 5 mph = 5 miles
3 hours at 4 mph = 12 miles
2 hours at 7 mph = 14 miles

5 + 12 + 14 = 31 miles

Posted in Brain Teasers

From Plant to Star

What plant becomes the name of a star by removing the first letter, becomes a number without the last letter and becomes a bird if the first and last letters are taken away?

Ivy

VY = VY Canis Majoris, one of the largest known stars
IV = Roman Numeral 4
V = representation of a bird

Posted in Riddles

Word Pronounced Incorrectly

What 11-letter word does everyone pronounce incorrectly?

The word “incorrectly”.

Posted in Riddles

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

Death By Marbles

You are a prisoner sentenced to death. The Emperor offers you a chance to live by playing a simple game. He gives you 50 black marbles, 50 white marbles and 2 empty bowls and instructs you to divide the 100 marbles into the two bowls. You can divide them however you want as long as all the marbles are in the bowls. You will be blindfolded and the bowls and marbles will be thoroughly mixed. You will then choose a single marble from one of the bowls. If the marble is white, you live. Black and you will be put to death.

How do you divide the marbles up so that you have the greatest probability of choosing a white marble?

Place one white marble in one bowl and place the rest of the marbles in the other bowl (49 whites, and 50 blacks).

This way you begin with a 50/50 chance of choosing the bowl with one white marble and living. Even if you choose the other bowl, you still have an almost 50% chance of picking one of the 49 white marbles. There are no guarantees in life, but this gives you the best change of surviving.

Posted in Brain Teasers