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, January 27, 2012

An Impossible Score


There was a lot of football talk this week in my household, as the New England Patriots advanced on to the Super Bowl. I asked my husband if he can suggest any football puzzle and he recollected the following story.

A number of years ago my husband discovered that our dentist and a long-time friend happens to be friends with Tom Brady's hairdresser, and occasionally gets invited to the Patriots games. From this moment on my husband's teeth showed a suspicious attraction to the dentist's office.  One day, after breaking cement of his tooth bridge, he even found himself in the dentist's home kitchen where he bumped into... who else but the Tom Brady's hairdresser himself, who was on his way to the game. Some football talk and a few hours later they all drove by our house to pick up our son for a Patriot's game.
Next morning my husband excitedly described to me the special box seats and how he almost met Giselle, while our son proudly shared with his summer-camp friends how late he stayed up, how tasty the hot dogs of Gillette stadium were and how noisy the football crowd was.

"What was the score?"  asked his counselor.
Our son named the score he remembered.
"That's impossible!" answered the counselor.

What could possibly have been our son's answer?

Top image by Not enough megapixels, distributed under CCL.

Your thoughts and ideas accepted any time until midnight on Sunday, January 29th(EST), on our Family Puzzle Marathon. They will be hidden till then and everyone who submitted something reasonable will get a puzzle point.

Friday, January 20, 2012

Great Packing Trick



Holidays are over and right now is about time to pack decorations into the boxes and shelve them somewhere for 11 long months. Assume that you have 40 identical plastic Christmas baubles that you carefully placed into a flat box like the one sketched below (top view). They fit tightly inside this box.

Suddenly you find another bauble from the same set. How to squeeze this bauble into the same box? Box has a height of one bauble, so no layering.

This puzzle is adapted from a Russian-language journal Kvant.
Top image by Chris_J, distributed under CCL.

Your thoughts and ideas accepted any time until midnight on Sunday Janury 22nd(EST), on our Family Puzzle Marathon. They will be hidden till then and everyone who submitted something reasonable will get a puzzle point.

Friday, January 13, 2012

Why things are not as they appear to be?

You are likely familiar with this sign on the side-view mirrors of some cars: "Objects in the mirror are closer than they appear." 


There are so many signs and instructions in the car that you probably avoid wondering about them up until your kids with their natural curiosity ask you: WHY? Let's try to run ahead of this question and figure out this WHY?
Why and how do you think these side-view mirrors distort reality?

 Image by Pratheep P S, www.pratheep.com, distributed under CCL.

Your thoughts and ideas accepted any time until midnight on Sunday Janury 15th(EST), on our Family Puzzle Marathon. They will be hidden till then and everyone who submitted something reasonable will get a puzzle point.

Friday, January 6, 2012

A 9-minute steak

This is a famous tricky puzzle wrapped in a new story.

You are a cook in a restaurant. A regular picky customer orders a steak that should be done in exactly 9 minutes. How can you measure these 9 minutes if the only precise clocks you have are a four minute hourglass, and a seven minute hourglass?

Top image by kamums, distributed under CCL.

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

Friday, December 23, 2011

Run buddy, run.

My husband has encountered this real-life puzzle last week and we are both looking forward to hearing your suggestions.


He wants to organize a running race at his work. His center consists of different groups. The group that will win the race will be awarded with a significant prize. We need your help defining the winner.

What does it mean for a group to win the race? Here are your guidelines:
  • Groups can be of different size, but each group should have equal chances to win.
  • Wide participation should be encouraged (and rewarded) more than running performance. 
  • Running performance should also be taken into account.
  • The runners that finish first, second and third should add special bonuses to their groups' total result count.

Therefore, in order to rank each group in this race we need some kind of a function that takes into account all of the above requirements, uses participation and run results and produces a number for each group. Group with the largest number would be declared the winner.

Top image by JerryFest, distributed under CCL.

Your thoughts and ideas accepted any time until midnight on Sunday December 25th (EST), on our Family Puzzle Marathon. They will be hidden till then and everyone who submitted something reasonable will get a puzzle point.

Friday, December 16, 2011

How long is the movie

It is a tradition in our puzzle marathon to dedicate a special puzzle to anyone who earns 10 puzzle points. This puzzle is for and about our puzzle master, Jerome.

A friend of Jerome's presented him with a DVD of a special movie he burned for his birthday. It may be the never-seen goofy movie from Jerome's wedding or  last year's Holiday party where Jerome was Santa. Jerome is riding a subway home and wondering how long this movie is and whether he will squeeze watching it at home before going out to celebrate at the restaurant. On the front of the disk it is written that disk capacity is 120 min, 4.7GB.  On the back   there is a clear separation circle between the inner "written" part (lighter area) and outer "clean" part (darker area).  Jerome looks carefully at his DVD (pictured below) and sees a solution. What is it?


Answer ideas accepted any time until midnight on Sunday December 18th (EST), on our Family Puzzle Marathon. They will be hidden till then and everyone who submitted something reasonable will get a puzzle point.

Pampers vs. Huggies


It has been 8 long years since we had a baby in the house, and transitioning along with our older kids we had completely forgotten all the baby nuances. One of them is how to avoid diaper changing in the middle of the night. It wakes you up, it wakes the baby up, the transition out from the cuddly warm blanket to the wet wipe on the baby's bare body in a cold room is a torture, it wakes your partner up, as well as the neighbors. Yet, the Huggies diapers that I purchased started to leak after 4 hours, making it impossible not to change in the middle of the night.

Is there any trick? I couldn't remember from my younger kids' days. I emailed my sister-in-law who recently had twins and all she replied was: "ONLY PAMPERS!!!!!"

Could it be so simple? I checked online and saw similar laconic advices everywhere on babies' forums.

I went to the store and bought the recommended brand.  Surprisingly they were exactly the same price as Huggies, like no one was in onto the secret.  We used it and, true enough, it doesn't seem to leak for 8-9 hours.

I know that more frequent diaper changes during the day is healthier, but for the night - the problem is solved. The question is: assuming that you leave a Pampers diaper on during the day for 4 hours and during the night for 8 hours, how much money you are saving as compared with Huggies diapers that you would replace every 4 hours night and day.  Let's compute it as a percentage of a diaper's price or assume that diapers are 3 for a $1.

Top image by dhinivh, distributed under CCL.

Answer ideas accepted any time until midnight on Sunday December 18th (EST), on our Family Puzzle Marathon. They will be hidden till then and everyone who submitted something reasonable will get a puzzle point.