Puzzles of the Week

main_thinkHere are some puzzles to pique your curiosity and sharpen and expand your mind…. maybe even blow it!

(If you’ve got a good one, please share it!)

Puzzle #1:

You are in a room with three light switches on a panel that does not control any of the light in your room.  One of the three switches controls a light bulb in another room that is off in the distance and not visible from your current location.  The other two switches have wiring that follows a path up and out of your room, but does not lead to the designated room with the light bulb.  The three switches are regular light switches which flip up for ON and down for OFF.  Without using any tools (including fellow humans), and being allowed only one visit to check that other room, HOW do you determine which of the three switches operates that light bulb in the other room?

Puzzle #2:

Two women enter an office lobby to apply for a job.  They look identical.  When they hand their job applications to the receptionist, that person notices the women were born in the same place, on the same day moments apart, of the same parents, and were given the same last name.  Everything is identical!  The receptionist says, “Wow, you must be twins,” to which the two women reply, “No.”

How can this be?


Puzzle #3:

A father & son are killed in car crash on a highway. The father dies instantly. The son is in very bad shape and must be airlifted to local trauma center for emergency surgery. The surgical team is scrubbing up, the head surgeon bursts into the operating room, takes one look at the boy on the table, steps back and says, “I can’t operate on him. This is my son!!”

How can this be?


Puzzle #4:

A man lives on the 12th floor of an apartment complex.  Each day he exits his apartment, walks down the hall to the elevator, takes the elevator down to the first floor lobby, exits the building, and goes to work.  At the end of the day, the man returns to the lobby and gets on the elevator.  If it’s been raining that day, or if there are other people on the elevator, he’ll ride all the way up to the 12th floor.  Any other time, he exits at the 10th floor and walks the remaining two flights of stairs up to his apartment.  Why is this?

Puzzle #5: (Compliments of student Pat M.)

You are on a river’s shore with 3 wolves and 3 chickens, and you need to get them all safely to the other shore using your boat. If wolves ever outnumber chickens, they will eat the chickens.  Your boat can hold you and 2 animals at a time, and you must have at least 1 animal on your boat for each trip across.  How should you proceed?


Puzzle #6:

A surgeon has one broken arm in a sling, and one arm available to perform surgery.  She has three patients to operate on, but she has only two surgical gloves.  HOW can she perform the three operations using the two gloves without risking contamination to her patients?


Puzzle #7:

You stand at a fork in the road. Next to each of the two paths, there stands a guard. You know the following things: 1. One path leads to Paradise, the other to Death. From where you stand, you cannot distinguish between the two paths. Worse, once you start down a path, you cannot turn back. 2. One of the two guards always tells the truth. The other guard always lies. Unfortunately, it is impossible for you to distinguish between the two guards.
You have permission to ask one guard one question to ascertain which path leads to Paradise. Remember that you do not know which guard you’re asking — the truth-teller or the liar — and that this single question determines whether you live or die.

The question is: What one question asked of one guard guarantees that you are led onto the path to Paradise, regardless of which guard you happen to ask? (That is, what do you ask, and what do you do?)

Puzzle #8:

“Packed as tight as sardines” is a commonly used phrase.  Why would a manufacturer who sells sardines packed in oil try to squeeze so many fish into each can?  Wouldn’t that hurt profits?  What’s the deal, and why do they do it?

Puzzle #9 (Compliments of Matt B – Period 2):

You walk into a room and see three (3) treasure chests. The first chest is labeled with a sign saying “100 Silver Coins,” the second is labeled “50 Silver Coins & 50 Bronze Coins,” and the third is labeled “100 Bronze Coins.”  However, each chest is mislabeled. You are allowed to take one coin from one chest without looking inside the chest (eyes closed). Which chest do you choose, and how do you determine which labels should go where?

Puzzle 10 (Compliments of Lauren D – Period 2):

The man who makes it doesn’t need it. The man who buys it doesn’t use it. The man who uses it doesn’t know it. What is it?

Puzzle 11 (Compliments of Lauren D – Period 2):

A man leaves home and turns left three times only to return home to two men with masks. Who are the two men?

Puzzle 12 (Compliments of Lauren D – Period 2):

Six logicians go out to eat, and the waiter asks if everyone wants coffee. The first five respond “I don’t know.” The last one responds “No.” Who wants coffee?

Puzzle 13: The Famous Monty Hall Puzzle

Suppose you’re on a game show, and you’re given the choice of three doors:  Behind one door is a new car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what’s behind the doors, opens another door, say No. 3, which has a goat. He then says to you,”Do you want to pick door No. 2?” Is it to your advantage to switch your original choice? Yes or No? (HINT: You want the car!)

Puzzle 14: (Compliments of Rob B)

There are 30 cows in a field and 28 chicken. How many did not?

Puzzle 15: (Compliments of Joey F.)

Gallahad, Lancelot and Percival are captured by an evil king. Being knights of the round table and therefore the evil king’s worst enemy, they are promptly condemned to death.The evil king, being a bit sadistic, offers the three knights a deal: He will let them go, if they can solve a riddle for him.
He puts all three of them lined up one in front of the other, all facing forward. Next, he puts hats on their heads. The hats are either black or white, and there is at least one of each colour. The way they are standing is the following: Lancelot > Gallahad > Percival. Each can see the colour of the hat in front of him, but not his own (in this way, Lancelot can see Gallahad’s and Percival’s hat, but not his own; Gallahad can only see Percival’s hat, and Percival can see no one’s hat). They are not allowed to communicate. If one of them can guess the colour of his own hat, the three are free to go. If they can’t, they will all be executed.They are given 30 minutes. No one says anything for ages, and then at the last minute, Gallahad figures out what his hat colour is, and they’re all freed. How did he do it?

Puzzle 16: (Compliments of Nikki M)

A prison guard watches a person visit a man in jail. When the visitor leaves, the guard asks the prisoner who the visitor was. The prisoner responds, “Brothers and sisters I have none. But that man’s father is my father’s son.”

Who is the visitor?


Puzzle 17: (Compliments of Matt B)

Oh, look! It’s a visual one! Read here and check out the pic:

You have a collection of wooden slabs like the one in the picture (with the dimensions provided). What is the smallest number of slabs you need to make a perfect square without cutting or altering the slabs in any way?

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Puzzle 18:

5 + 5 + 5 = 550

By adding one straight line to this equation, make it correct.

Puzzle 19:

A doctor, scientist and kindergartner come across a ping-pong ball stuck inside the bottom of a pipe (tube), and they’d like to try to get it out.  This pipe is secured in the ground in solid concrete, and it protrudes about 1-foot out of the ground.  It is also just barely wide enough for the ball.  They have a hammer, a shoelace, and a handkerchief to use, but the doctor and scientist give up after a few hours.  The kindergartner, however, has an idea that should work without damaging any of the items, including the pipe or the ball.  What’s the idea?


Puzzle 20:

What’s the rule to dictate why some letters are on the top line, and some are on the bottom?

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Puzzle 21:

There are no tricks, just pure logic, so good luck and don’t give up.

  1. In a street there are five houses, painted five different colors.
  2. In each house lives a person of different nationality
  3. These five homeowners each drink a different kind of beverage, smoke different brand of cigar and keep a different pet.



  1. The Brit lives in a red house.
  2. The Swede keeps dogs as pets.
  3. The Dane drinks tea.
  4. The Green house is next to, and on the left of the White house.
  5. The owner of the Green house drinks coffee.
  6. The person who smokes Pall Mall rears birds.
  7. The owner of the Yellow house smokes Dunhill.
  8. The man living in the centre house drinks milk.
  9. The Norwegian lives in the first house.
  10. The man who smokes Blends lives next to the one who keeps cats.
  11. The man who keeps horses lives next to the man who smokes Dunhill.
  12. The man who smokes Blue Master drinks beer.
  13. The German smokes Prince.
  14. The Norwegian lives next to the blue house.
  15. The man who smokes Blends has a neighbor who drinks water.




Puzzle 22:

A bookworm eats his way from page 1 of Volume 1 to the last page of Volume 2 of a 2-Volume work.  The books are standing on a bookshelf in the usual manner with the binding facing out.  If the pages of each volume are 3-inches thick, and the covers are one-half-inch thick, through how many inches did the bookworm chew?

(HINT:  the answer is NOT 6-1/2 inches!)


Puzzle 23:

‘Packed as tight as sardines’ is a commonly used phrase.  Why would a manufacturer who sells sardines packed in oil try to squeeze so many fish into each can?  Wouldn’t that hurt profits?  What’s the deal, and why do they do it?


Puzzle 24:

This week’s puzzle comes from the NPR “Car Talk” guys…

A landscaper returns from work and is sitting at the kitchen table with his kids. The kids ask, “Did you work hard today, Daddy?”

Dad says, “I did. I planted five rows of four trees each.” His little third-grader, wanting to show off her newfound skills with the multiplication tables, says, “You planted 20 trees, Daddy!”

He says, “No, I’m sorry, you little twerp. That’s wrong. I planted 10 trees.” She responds, “That’s impossible!”

The dad responds, “No, it isn’t, and here’s a hint: If you look at one of the math or history test papers that your teacher has returned to you recently, you’re going to find the answer.”

The little girl sits there and thinks for a minute, and then she says, “I’ve got it!”

What did she find on her paper that gave her the answer?


Puzzle 25:

A sweater worn in typical fashion has the label on the inside back of the collar.  Assume that the sleeve that accommodates the left arm when worn normally is called the left sleeve, and the one that accommodates the right arm is called the right sleeve.  Where will the label be if the sweater is turned inside out with the right arm put into the left sleeve, and the left arm put into the right sleeve (front outside, back outside, front inside, or back inside)?


Puzzle 26:

Which continent has the highest per-capita percentage of Ph.Ds?  (HINT:  If you give this the appropriate level of thought, everyone should be able to get it!)


The Hardest Logic Puzzle Ever:

Thanks to Zachary Potter, former student, here’s a puzzle he sent in for us all.

As per request of The Metz, heres “The Hardest Logic Puzzle Ever” (from Wikipedia):

“Three gods A, B, and C are called, in some order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter. Your task is to determine the identities of A, B, and C by asking three yes-no questions; each question must be put to exactly one god. The gods understand English, but will answer all questions in their own language, in which the words for yes and no are ‘da’ and ‘ja’, in some order. You do not know which word means which.”

And some clarifications:

“It could be that some god gets asked more than one question (and hence that some god is not asked any question at all).

What the second question is, and to which god it is put, may depend on the answer to the first question. (And of course similarly for the third question.)

Whether Random speaks truly or not should be thought of as depending on the flip of a coin hidden in his brain: if the coin comes down heads, he speaks truly; if tails, falsely.

Random will answer ‘da’ or ‘ja’ when asked any yes-no question.”

You can visit the Wikipedia page (linked at the top) for hints and possible answers.


Puzzle 27:

You have 8 coins, all of which look, feel and smell identical.  One of the coins is bogus; it’s heavier than the other seven.  You also have a balance scale, on which you can put coins on each side and compare their weights.  HOW can you take the 8 coins and determine which is the bogus, heavier coin, with just two weighings?


Puzzle 28:

Between 12:00 midnight and 12:00 noon on a digital alarm clock, how many times can you find three (3) of the same digits consecutively in a row (e.g. 1:11, 2:22….)?


If you had fun with this one, you should enjoy the link below. One of my former students, Andy Mikulski, created this clever digital solution…



Puzzle 29 (Compliments of Zaria):

A monkey, bird, and squirrel are racing up a coconut tree. Who gets to the banana first?


Puzzle 30 (Compliments of Danielle)

There are three coffee sacks placed in front of you. TWO of them are empty & ONE is filled with coffee beans. How do you take the ONE full bag of coffee beans and FILL the TWO empty ones?


Puzzle 31 (Compliments of Alicia C)

Here is a series of numbers. Based on the pattern, provide the next number in the sequence.

1, 11, 21, 1211, 111221, 312211,…


Puzzle 32 (Compliments of Imari L):

Everyone has it but no one can lose. What is it?


Puzzle 33 (Compliments of Joy S):

What has oceans without water, beaches without sand, cities without people, and mountains without land?