The Pattern of Numbers

These series follow a pattern.
2 4 8
1 17 476
65 20987 3571890

This series does not follow the pattern
18 79 45

What is the pattern?

The numbers must be in ascending order. This can be a fun one to have people work out in person, as they test out three-number series and you can tell them whether or not they satisfy the pattern.

Thanks to Patrick for sending this in and thanks to this video from Veritasium for inspiring Patrick.

Posted in Brain Teasers

Building With the Most Stories

What building has the most stories?

The library.

Posted in Riddles

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

Often There’s Only a Frown

I torture children and parents
Many people scream and wail in my presence
Parents drag their kids to me
I am supposed to create smiles,
But often there is only a frown.

What am I?

A dentist.

Posted in Brain Teasers
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Why This Particular Order?

Why are these letters grouped in this particular order?

1) DFGHLPRU
2) KSTV
3) CO
4) AIW
8) MN

The letters are grouped by the number of U.S. States beginning with that letter. M and N are tied for each starting eight states.

Posted in Brain Teasers

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

3661 Seconds Past Midnight

What is special about 3,661 seconds past midnight on January 1, 2001?

At the 3,661st second, the time and date can be written 01:01:01 01/01/01.

That is one cool date :)

Posted in Brain Teasers

Dwarves and Snow White

The dwarves and Snow White sit down for a bite.
How fast can you guess what she serves her guests next?

Seven Seconds

Posted in Riddles

Mixed Animals for $100

At the market you can buy a cow for $10, a pig for $1 and 8 hens for $1. How many animals would you need to buy to get 100 mixed animals for exactly $100?

7 cows, 21 pigs and 72 hens. The trick to this is finding the combination of cows and hens with the same cost and quantity since pigs are already equal. The magic combination is 7 cows and 72 hens, giving you 79 animals that cost $79 ($70 + $9). Then you just add 21 pigs to get to 100 animals.

Posted in Brain Teasers

Sleeping Killer

A man gets ready for bed at 9:45 pm. He makes himself a drink, then turns off the TV and the lights. The night was windy and there was a major storm. The next day he discovers he was the cause of seven deaths. How is this possible?

He lived in a lighthouse as lighthouse keeper. He turned off all the lights by accident, so a ship with 7 passengers couldn’t negotiate the rocky shores. One would think the light switches in a lighthouse would be more clearly marked.

Posted in Brain Teasers