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!

## Friday, July 25, 2014

### Shortest Way to Help Grandma

Good news: The solution time has been extended till Friday as by technical reasons the newsletter didn't go on time.

You and your grandma live on the same side of the river. You need to find the shortest way to walk from your house to the river (with an empty bucket), fill the bucket with water and bring the water to your grandma. The river is fierce and you cannot swim in it.  Disregard the fact that it is much harder to walk with a full bucket than with an empty one. Just look for the shortest path.

Note: the solution does not involve any equations, just one-two simple lines.... Feel free to print the image or redraw it. Submit your answers as images via email to me or in the comments on this blog post. Please explain your answer. The answers are accepted any time until midnight Eastern Time on Friday, on our Family Puzzle Marathon

Friday is here and below is the answer drawing:

The shortest way is marked with a red line.
To find it draw a reflection of the grandma's house across the river and connect with a straight line Your house and the Reflection of Grandma's house. It surely is the shortest distance between these two points.
But Grandma lives on this side of the river! OK, just reflect the interval of the line from the river to Grandma's house.

## Friday, July 4, 2014

### What does it take to change an Army?

Here is a new great puzzle my coworker shared with me. By the way, he is in a delivery room right now waiting for his twin boys to emerge. All the best, Jonathan!

In a faraway land, the Queen's Army consists of 3 Corps.

Each Corp is composed of 3 Divisions.
Each Regiment of 3 Companies.
And finally each Company of 3 Soldiers.
Soldiers are either Air Force soldiers or Marines

Now, the rules, from the bottom of the hierarchy to the top:
Each Company is composed of either:
2 Air Force soldiers and 1 Marine (in which case it is named The Air Force Company)
or
2 Marines and 1 Air Force soldier (in which case it is named The Marines Company)

Each Regiment is composed of either:

2 Air Force Companies and 1 Marine Company (in which case it is named The Air Force Regiment)
or
2 Marine Companies and 1 Air Force Company (in which case it is named The Marines Regiment)

and so on till:

Each Army is composed of either:

2 Air Force Corps and 1 Marines Corp (in which case it is named The Air Force Army)
or
2 Marines Corps and 1 Air Force Corp (in which case it is named The Marines Army)

At the present time the Queen's Army is Marines Army. However Queen's new lover is an Air Force pilot and he convinced the Queen to change the Army to the Air Force Army. The question is: what is the minimum number of soldiers that the Queen needs to change so that her Army will become The Air Force Army?
The answers are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

## Friday, June 27, 2014

### Hong Kong Elementary School Admission Test

Can you solve this in 20 seconds?  If not, perhaps you are like I not ready for the 1st grade.
Try it on your iPad or a Smart Phone, this could help:)

The answers are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

## Friday, May 30, 2014

### An Olympic Torch Puzzle

Two people are running around the Olympic stadium in the same direction. One of them is a much faster runner than another. They have only one torch and they pass this torch to each other every time one of them is crossing another. They start from the same spot and the faster runner holds the torch at the start. At the end f the race, the faster runner made 50 loops, the slower 35. How many loops made the torch?

Hint: assume that instead of one torch they have another item (say a newspaper) that is starting in the hands of a slower runner and is being exchanged for a torch every time the runners pass each other.

This puzzle came from Israeli newspaper Haaretz.

The answers are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

## Friday, May 2, 2014

### Riddles

Lets try as an appetizer the riddle my coworker shared with me:

1. The more you take from it, the larger it becomes. What is it?

And now munch on a few number riddles sent by Lulu:
1. I am worthless as a leader, but when I follow a group their strength increases tenfold. By myself I am practically nothing, neither positive nor negative.
2. A word I know, six letters it contains, subtract just one and twelve remains.
3. Five hundred begins it, five hundred ends it, five in the middle is seen. First of all figures, the first of all letters, take up their stations between. Join all together, and then you will bring before you the name of an eminent king. (hint: use non-Hindu-Arabic numbers)
They are short but not necessarily easy. You can ask your kids for help. Please reference puzzle numbers in your answers. The answers are accepted any time until midnight Eastern Time on Sunday, on our Family Puzzle Marathon

## Thursday, April 24, 2014

### Marathon Birthday Puzzle

This week my friend Irina complained to me that her son's 17th birthday fell on the Boston Marathon Day and friends weren't able to come and celebrate with them in their Brookline home until the roads opened. Previous such coincidence was 17 years ago when her son Daniel was just born in the Beth Israel Hospital that is right along the marathon route and all the visitors got delayed till the end of the marathon festivities. Irina mused that I could probably calculate when the next such coincidence would happen and I thought why not turn it into a puzzle.

Daniel's birthday is April 21.
Boston Marathon is held on Patriots Day that is 3rd Monday in April.
Is Irina correct that the Boston Marathon coincided with Daniel's birthday only twice: in 1997 when he was born, and now in 2014? When is the next time such a coincidence will happen?

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

## 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 ....