Matchsticks – make 3 squares

1) Make 3 squares^*

Move 2 matches to make 3 squares of equal size.

This problem comes from J.A.H. Hunter

You can check your solution here

Did you know?
Recent research shows that learning new skills keeps an aging mind sharp.
Lead researcher Denise Park of the University of Texas:
It seems it is not enough just to get out and do something—it is important to get out and do something that is unfamiliar and mentally challenging, and that provides broad stimulation mentally and socially. When you are inside your comfort zone you may be outside of the enhancement zone.

Yes/No

There is a well known family game where one person takes an object in mind, and the rest of the company may ask yes/no questions and have to guess what it is.

Example:
A: OK, I’ve got something in mind
B: Is it something I can touch?
A: No.
B: So it is something abstract?
A: Hm, no
C: Is it something I can hear?
A: No
D: Is it something I can see?
A: Yes!
B: Is it inside the house?
A: No
C: Can it always be seen?
A: No
D: Just on certain days?
A: Question not clear, but probably no.
and so on.
(btw, if you want to know what A has in mind, you can ask me yes/no questions at the bottom of this page)

This kind of game consists of a series of puzzles. There is a variant, in which baffling stories are presented, and people may ask yes/no questions to explain the situation.

Well known examples are:
A) A man goes down with the elevator everyday. When he returns from work, he goes up half way, and takes the stairs. Unless it rains, then he goes up all the way.
B) A man is lying in a meadow. He is dead. Besides him there is a white package.
c) A man walks into a saloon. The bartender pulls his gun at the man. The man says: “thank you” and leaves the saloon.
I first heard these puzzles when I was a teenager, and you can find the solutions on several places on the web.

For those who are interested in this kind of puzzle, Paulo Sloane runs a forum with this kind of puzles at www.lateralpuzzles.com. He is also the author of the book “Lateral thinking puzzlers”.

Complete the alphabet (4)

1) Complete the alphabet^*

ACDEHIMNOTU
BFGJKLPQRSVWXY

In which row does the letter Z go?

If you solved it, we have the solution

This brainteaser was published in the British magazine “Games and Puzzles”.

Four fours

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Using exactly four fours, create the numbers 0-30. You may use the usual mathematical operands, but not squaring, as this requires a number 2. You may use brackets.
Example: (4+4)-(4+4)=0

As always, please don’t publish your solutions. Solutions can be found after 1-2 weeks on the solution page for those who want to check their solutions, or for those who are really stuck.
But scrolling is much easier, and really spoils the fun for others.

I am very much interested in your solution times, and I welcome your remarks and criticisms. Pointing out alternative solutions is also welcome, as they point out possible problems in the brain teasers.

If you are puzzled, we have a solution for you.

This puzzle has a long history. When I still was a teenager, my father challenged me to make all numbers 0-20 using the digit 4 exactly 4 times. Recently I shared this puzzle with some fellow consultants. Kees Krol arrived at the office one morning and announced he had extended the range all the way to 30. 🙂

Matchsticks – make 10 squares

Move 5 matchsticks to create exactly 10 squares.

Can you find both solutions?
The credits for this puzzle go to my daughter Margreet. The credits for the second solution go to Kees Krol.

As usual, you are welcome to report your solution times and comment on the solution, but please do not give away the answer – that may spoil the fun for others. I will publish the solution in one or two weeks after posting the puzzle.

You can check your solution here

two ropes

This week’s brain teaser comes from IitianWay, and I’d like to thank him for communicating it with me:

I have two ropes. Both are 1 meter long. Both will burn for exactly 1 hour. However, the speed with which they burn need not be evenly distributed over a rope. For example, the first 30 cm may burn in 30 seconds, while the other 70 cm takes the remaining 59,5 minute to burn.

How can I use them to measure 45 minutes?

As usual, you are most welcome to report your solution times and comment on the solution, but please do not give the answer – that may spoil the fun for others. I will publish the solution in one or two weeks after posting the puzzle.

You can check your solution here