Dead presidents: spell or coincidence?

Do you know that three of the presidents of the United States died on the same date, with the date being not just a random date but the most special date for the country - July 4th. John Adams and Thomas Jefferson both died on July 4th of 1826. Five years later, on July 4th 1831, the fifth president, James Monroe, passed away. All three are believed to have died of natural causes.

If you become a special adviser to the president, would you point to the president such an impossible coincidence and advice your president to take the July 4th off and relax avoiding the suspicious spell.  Or would you explain such coincidence in some other way?

Top image by JaseMan, distributed under CCL.

Answer ideas accepted any time until midnight on Saturday October 8th (EST), on our Family Puzzle Marathon. They will be hidden till then and everyone who submitted something reasonable will get a puzzle point.

Handshaking at the UN meeting

A whole lot of people shook hands and a whole lot refused to shake hands with each other at the currently happening UN meeting in NYC.  As UN handshaking is not just a handshaking but a political statement, all these handshakes were carefully monitored and accounted for by the special math agent Ilya 011. Where 011 stands for his ranking in this puzzle marathon.

At the end of the meeting Ilya reported that something fishy is going on as the number of people that shook odd number of hands is an odd number and this is impossible. He was right. It turned out that President Obama extended a handshake to Prime Minister Netanyahu but the latter refused it. The rest of the recorded handshakes were mutual.
The question is: how did Ilya knew to suspect the handshaking statistics?

Disclosure: this puzzle celebrates our 10+ puzzle points winner Ilya. The rest of the characters and events in this puzzle are fictional. Any resemblance is purely accidental.

When two people extend hands for a handshake, this counts as one handshake for each of them. At that time two handshakes total are being recorded and added to the total number of handshakes.

Top illustration by Aidan Jones, distributed under CCL.

Answer ideas accepted any time until midnight on Saturday October 1st (EST), on our Family Puzzle Marathon. They will be hidden till then and everyone who submitted a valid solution will get a puzzle point.

Post-election Party

Photo from Flickr distributed under CCL

Mid-term elections. 2010. You did it! Yours and others volunteer work and donations placed your candidate at the post. Supercharged with excitement you are celebrating at the post-election victory party. Unfortunately, you are also exhausted and can't locate your watch. When you ask an attractive woman next to you what time it is, she presumes you are drunk. "Let's see if you are capable to drive" she says. "If you stay an hour longer, it will be three time more past midnight than it is now. What time is it now?"

Note: your answer won't be visible untill Saturday morning. Everyone who answers correctly will get a puzzle point. These are new rules of our Family Puzzle Marathon. Solve 5 puzzles and we will send you a prize. Solve 10 and we will write a puzzle about you.

Math can save lives, admiral!

During the Second World War, the British Army adopted a naval convoy system for all their merchant ships. Each convoy consisted of 30-70 freight ships and was surrounded by patrolling ships or airplanes. To minimize the chances of convoy being discovered and bombarded by the enemy submarines, the commandment considered two options: sending each convoy as one big flotilla, or splitting the convoy into a few smaller convoys and sending each separately. Can you help the commandment to make this decision?

Naval convoy usually consist of a few merchant ships surrounded by escort ships or airplanes. Looking from the air, we could approximate a convoy as a large blob or circle on the water. What do you think will have higher chances of safely arriving to the destination, one big blob or few small ones?

A Chain Loan

Greek Government recently got a $140 billion aid package from the International Monetary Fund. Imagine that International Monetary Fund would like to get some symbolic collateral for the loan and is eying an ancient gold link chain (believed to belong to Aphrodite) from the Athens's Museum. The chain has only seven links, all connected in a row. Monetary Fund wants one link for each year until the loan is returned. Meaning that it wants to hold to one ring in the first year of the loan, two rings in the second, three in the third etc. Greek government agrees but demands that chain be minimally damaged and only one link out of the whole chain be cut. Is that possible?

Submit your answer on our Family Puzzle Marathon Be first to solve three puzzles and get a prize!

A Question of Collar

Buying a shirt for Valentine's Day? You thought knowing the neck size and sleeve length is enough? Turns out shirt collars come in different lengths and angles! Some are long and pointy, some are short and wide-angled.
Here are some presidents' necks in collars from New Yorker photographer Platon, shot at a United Nations meeting recently. All these men have been dressed with the help of a fashion adviser. Yet, their collar choices are so different.







How do you choose a collar?
What factors do you take into account to pick a collar for yourself or someone you know?

Do you consider the shape of your face?
Your height?
Pattern of the shirt or the tie?
Political affiliation?
Fashion trends?

Please enter your ideas about the math and fashion of shirt collar selection on our Family Puzzle Marathon page.

White House State Dinner

Imagine that you have been invited to a White House State Dinner. Or a fancy formal Thanksgiving Dinner. You observe the exquisite plate setting in front of you and realize that you have no idea with which of the two spoons you are expected to touch the pre-dinner sorbet (palate cleanser).



You are desperately trying not to reveal your ignorance to a very attractive person sitting across the table from you. So, you decide to quickly ask a person to your right or a person to your left, neither of whom have been served the sorbet yet. The problem is that you have been informed that one of the people that is sitting right next to you is a chronic liar. But you do not know which one. What one brief question can you ask from either of your neighbors, that will clarify the spoon approach for you?

Submit your answer on our Family Puzzle Marathon site. Solve three puzzles and get a prize!

Castle Doors

You find yourself locked in a castle, where the only two doors out are guarded by two men. One of these men always lies and one of them always tells the truth. Unfortunately, you do not know which man is which. One of the doors leads to freedom and one to captivity. Determine a single question that you may ask one of the guards that would reveal the door to freedom with certainty.

This is yet another puzzle from the Fermat's Theorem movie described here.


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The Secret Meeting

At the recent UN meeting, president Obama decided to invite a number of other party leaders for a private meeting. No one knows who exactly and how many people were invited to this secret meeting, but rumor says it that a lot of handshaking was going on there. Every leader entering the meeting was approaching everyone already present in the room and shaking hands. Obama mused that something around 78 handshaking moments have happened at this meeting. How many people were invited?

Submit your answer on our Family Puzzle Marathon site. Solve three puzzles and get a prize!