Subscribe to get new riddles and brain teasers once a month

Three Cuts to Turn a Round Cake Into Eight Equal Slices

How can you cut a round cake three times to make eight equal slices?

Cut #1 – Down the center of the cake (vertically) leaving two equal halves.
Cut #2 – Across the center of the cake (horizontally) leaving four equal slices.
Cut #3 – Through the middle edge of the cake slicing all four of the pieces in equal halves, leaving eight equal slices (four equal tops and four equal bottoms).

Posted in Brain Teasers

Okeechobee Burial

Why can’t a man living in Okeechobee, Florida be buried west of the Mississippi River?

Because the man would surely object to being buried since he’s living in Okeechobee.

Posted in Brain Teasers

Which Do You Light First?

You have a single match and are in a pitch black room with a candle, an oil lamp and a gas stove. Which do you light first?

The match.

Posted in Brain Teasers

How Many Months Have 28 Days?

Some months have 30 days and some have 31 days. How many months have 28 days?

All of them. Every month has a day 28, even though some continue on after reaching 28.

Posted in Brain Teasers

Three Pills From the Doctor

Your doctor gives you three pills and tells you to take one every half hour. How much time will have passed by the time you’ve taken all three pills?

One hour. You take the first pill, then wait a half hour and take the second pill, then at the hour mark you take the third and last pill.

Posted in Brain Teasers

What is the Chance That You’ll Be Correct?

If you choose an answer to this question at random, what is the chance that you will be correct?

a) 25%
b) 50%
c) 60%
d) 25%

I consider this paradox, because it’s self-referential. Both A and D would be correct if there were four unique answers, but since A and D are the same answer, the chance that you would choose a correct answer is 50%, which makes B correct. But if there’s only one correct answer, the odds of choosing the correct one at random goes back to 25%. And around and round you go.

There’s a lot of discussion at Richard Wiseman’s blog and more at Lifehacker, where I first saw this.

Posted in Brain Teasers

1 2 3 4 5 6 7 8 9 = 100

This equation is incomplete: 1 2 3 4 5 6 7 8 9 = 100

One way to make it accurate is by adding seven plus and minus signs, like so.

1 + 2 + 3 – 4 + 5 + 6 + 78 + 9 = 100

How can you do it using only 3 plus or minus signs?

123 – 45 – 67 + 89 = 100

Posted in Brain Teasers

Door Body and Knot

A door, a body, and a knot can be this.

Double. Double doors, a stunt double (for an actor) and a double knot. And there’s also the double rainbow :)

By Sef Daystrom

Posted in Brain Teasers

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

BEJQXYZ

What is significant about the following set of letters?

BEJQXYZ

They are the only letters in the alphabet that are not found at the beginning of the name of a state in the United States of America. The rest of the letters in the alphabet, namely ACDFGHIKLMNOPRSTUVW, start the name of at least one state. Incidentally, eight different states each start with the letters M and N, tying them for the most states starting with a particular letter. The next highest is a three-way tie between A, I and W with four each.

Posted in Brain Teasers