Announcing a Puzzle Marathon

Puzzles for every age and taste. Share them with your family at the dinner table, solve them with your co-workers during a coffee break, use them to spark a conversation during car ride. Puzzles are math presented as a candy.

New puzzle is posted every Friday. You can submit your answer anytime on Friday, Saturday and Sunday. The answers will not be visible. All the answers will be revealed on Monday morning, East Coast time. Everyone who solved the latest puzzle correctly will get a puzzle point. Solve 10 puzzles - and we will write a puzzle about you!

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Friday, April 4, 2014

Must See Movies



One friend is telling another:
- I am going to recommend you 5 movies each of which will completely turn your life upside-down.
One month later:
- Did you see my movies?
- Yes, I did.
- What do you think?
- Oh, I should have stopped after the ....

Your task is to complete the last sentence and provide the explanation to your answer.
This puzzle came from my co-worker Ira.

Your thoughts and suggestions are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

Thursday, March 27, 2014

A Simple Magic Square

Magic squares are tables of numbers where sums of every row, every column and both diagonals produce the same number. No, they were not invented by Ben Franklin, but have been around for thousands of years before. Take a look at this one on Gaudi’s Sagrada Família church in Barcelona:


Now, a little Magic Square puzzle suggested by our reader Lulu:

There is a 3 X 3 table with 9 cells in it and we are required to fill in the table with numbers from 1 to 9. Each number can be used only once. The numbers have to be placed in such a manner that they add up to 15 horizontally, vertically and diagonally. Can you do it?

Your thoughts and suggestions are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

Friday, March 7, 2014

Four Women and Four Hats Puzzle


Once upon a time four women bought four hats. All the hats were black inside. Two of them were while on top and two black on top as in the picture below. In this game, three women (Beth, Iris, Michelle) were asked to stand inside the room facing each other's back, and the fourth (Katy) was left behind the wall.  Everyone was allowed to look only forward. Michelle saw Beth and Iris'es heads. Iris only Beth's head. Beth and Katy were facing the non-reflective wall. Then the hats were placed on their heads.


No woman knew what color hat she has, only that there are two white and two black hat overall. They were asked to figure out their hat color. No guessing was allowed, just pure logic and definite answer. They were all very savvy. After a minute of silence one of them announced her hat color. And she was absolutely right. Who was it and how did she figure it out?

This puzzle came from my daughter's friend (10-years old) and they had great time enjoying it at school. You can do it as well!

Your thoughts and suggestions are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

Friday, February 28, 2014

Oscar Ropes Puzzle

We are done with the winter Olympics and now are looking forward to the Oscar's entertainment. 
As we saw in the previous puzzle, the most interesting stuff happens away from the main arena and escapes the media attention:)   And what do we have on the margins of the Oscar ceremony? VIP ropes and poles that guard the Red Carpet attendees, of course. 



This a puzzle about two poles, 5 feet high each, and a rope connecting these poles. The rope is 6 feet long and at its lowest point is 2 feet above the ground. The question is: how far away are those poles?

This puzzle came from my son's friend Adam. Thank you!

Your thoughts and suggestions are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

Thursday, February 13, 2014

An Olympic Puzzle



February 2014. Russia, Sochi.
Taxi drivers in the city are very busy bouncing all the athletes and spectators in-between the Olympic village and the city. This is a puzzle about two taxis: say Green and Yellow. Green taxi starts from the village and goes toward the city exactly at the same time when Yellow taxi leaves the city in the direction of the village.  They drive toward each other and meet (for the first time) 5 km from the village. Each delivers its passengers and immediately returns back with the new riders: Green taxi now drives from the city to the village while Yellow taxi returns from the village to the city. They meet (for the second time) 3 km from the city.
The question is very simple - how far is the Olympic village from the city?
Here is the sketch created by Kimberly Rose that should help you.



Note that this puzzle is fictional and Googling the real distance will not provide the answer. The puzzle is adapted from a summer boat puzzle from my favorite book of puzzles:

 

Your thoughts and suggestions are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

Friday, February 7, 2014

How does it work?

Here is a number magic trick that came to me via mail.
All of you, math detectives, are invited to unveil its magic with your logic.
  1. Take the last digit of your mobile phone number.
  2. Multiply this digit by 2.
  3. Add 5 to the result.
  4. Multiply what you got by 50.
  5. Now, you may need a calculator. Add to the previous result 1763. And if you already celebrated your birthday in 2014, add another 1.
  6. Last step! Subtract the year of your birth.
You should now have a 3-digit number.
Its first digit is the last digit of your mobile phone number and the next two digits are your age!


How does it work? Your thoughts and suggestions are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

Friday, January 17, 2014

Parrots and Cages puzzle

You have 42 parrots and 7 cages of various sizes. Lock all the parrots inside the cages so that no cage is empty and each cage contains an odd number of parrots.

A hint: this puzzle requires some unusual thinking.
Warning: the solution is below.


At first it seems simple: 42 divide by 7, 6 parrots in each cage. But the number of parrots in each cage should be odd. OK, let's try 1 parrot in each of the first 6 cages. How many parrots are left? 42-6=36. Put 36 in the last cage. Again, not an odd number. 

Now we note that in general, there is no way that 7 odd numbers could be added to produce an even number. So, there must be a trick! A trick that does not involve the numbers. 

And the trick is to place cages inside each other. There was a note of cages being of different sizes. So, place one parrot inside a small cage, place this cage inside a large cage. Both cages have odd number of parrots. You are left with 41 parrot and 6 cages. Now, it is easy. Anyway you do it, it works. Just keep numbers odd.

You can try this puzzle now on your friends and family if you are not afraid to be beaten.  A simpler version of it is to pack 6 presents inside 7 boxes of various sizes so that no box is empty.
Enjoy!