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 28 days. Some just 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%

This is becomes a self-referential paradox. 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.

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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

How Can You Pass the Tree

A car is on a narrow road with a tree in the middle of it. How can the car pass the tree?

The tree is in the middle of the road as measured by length, not in the middle of it by width. In other words, the tree is growing on the side of the road, but it is equidistant from either end of the road, and therefore in the middle.

This makes it quite easy to pass the tree as you just drive on the road, unless you’re texting and you run into said tree. If this is the case, stop texting.

Thanks to everyone’s input on this one!

Posted in Brain Teasers

Strip Ground Fan

What one word goes with each of these to make a new phrase?

Strip
Ground
Fan

Out. Strip out is to remove parts from a machine. Ground out is when you hit a ground ball in baseball and are thrown out at first. Fan out is when something, such as cards, are spread out like a fan.

Thanks to Jeremy for solving this.

Posted in Brain Teasers

Evianna’s New Love Interest

Evianna meets a man while attending her mother’s funeral. She becomes infatuated with him and he reciprocates the interest, but he leaves the funeral without giving her any contact information. She tries to locate him but is unsuccessful. Several days later she kills her sister.

Why did she do it?

Because she’s a psychopath. She killed her sister because she hoped the man would attend the funeral and she would get to see him again. This is one brain teaser that is probably best that you don’t get the correct answer. If you knew the answer right away and thought it was obvious, you may want to talk to someone.

Posted in Brain Teasers