10 Puzzleswith Solutionsby Fabrizio Valerio Covone

Puzzle 1A spy wants to enter in a top secret building, but the guard at the entrance asks everyone a password.For this reason the spy hides out and wait for someone, so he can have a peek. A person comes and the guard says:“Wait! If I say six which is the password?”“Three!”“Ok, come in.”The spy thinks: “mmh… I guess how it works…” But to be sure he keeps hiding and wait for another person. Another one comes:“Hold on! If I say twelve which is the password?”“It’s six!”“Ok, come in.”“Ok I got it” the spy thinks and try enter, but obviously is stopped by the guard asking the password:“Hey you, wait! if I say eight which is the password?”“I bet it’s four!”The guard in second takes his gun and shoots down the spy.Which was the right answer?

Puzzle 1

The right answer is five!Because the guard wants to know the exact amount of letters of the number he says instead of the division by 2.

Puzzle 2A spaceship has a failure and auto-destruction activates itself. The 20 people crew have exactly 13 minuets to escape from such a deadly trap.But the safety escape pod is capable to carry a total of 4 people and there aren’t any space suites. Furthermore, a trip to the nearest planet and back takes 3 minutes.How many people will survive?

Puzzle 2

There is enough time for 5 trips before the spaceship blows, but since starting from the 2nd trip one place is taken by the pilot.4 + 3 + 3 + 3 + 3 = 16So, only 16 crew members will survive.

Puzzle 3An explorer finds a secret chamber in a pyramid. Inside the chamber there are 7 identical metal bars and a rusty 2 scale pans balance.An inscription on the wall says that only 1 of the metal bars is made of gold the other ones are made of pyrite (a metal similar to gold but slightly heavier and worthless). The explorer wants to take only the gold bar, but he is very lazy and wants to figure it out doing as less weightings as possible.

Which is the minimum number of weightings?

Puzzle 3The right answer is 2.During the 1st weighting the explorer will put 3 metal bars on each scale pan. If the pans are balanced then the gold bar is the one not on the pans.Otherwise, the explorer will take the lighter 3 bars group and puts one metal bar on each scale pan.Following a similar procedure, if the pans are balanced then the gold bar is the one not on the pans.Otherwise the lighter one is the golden bar.

Puzzle 4A, B, C and D are single-digit numbers.The following equations can all be made with these numbers.Find the values of each digit.

A + B = DB − A = C2 × C = 8D ÷ 3 = 2

Puzzle 4The right answer is:A = 1B = 5C = 4D = 6As a matter of fact the equations with correct values are:1 + 5 = 65 − 1 = 42 × 4 = 86 ÷ 3 = 2

Puzzle 5Have a look at this wonderful example of modern art.How many squares can you see?Be sure to count overlapping squares separately.

Puzzle 5The right answer is 22.

Puzzle 6Only one of these pictures can be drawn with one line without lifting your pen from the paper or retracting any lines.Which one is it?

Puzzle 6The right answer is B.

Puzzle 7During lesson break someone ate all classroom snacks, interrogated by the teacher the 3 students in the classroom gave the following statement:A:“C is lying, I saw him eating the snacks.”B: “I didn’t see anything.”C: “B is a liar, I saw him taking the snacks from the bags. ”

Only one of them is saying the truth. So, who ate the snacks?

A B C

Puzzle 7

B is the snack thief, because only C is telling the truth.

A B C

Puzzle 8Three of the four shapes below can be combined to form a square. Which one isn’t used?Feel free to rotate the shapes.

A B

C D

Puzzle 8The right answer is A. Below you can see the square as a result of B, C and D combination.

B C

D

Puzzle 9

Joe forgot his wedding anniversary, but thanks to his brand new smartphone he got a reminder just 1 hour before his wife’s alarm rings. Now he has to buy a present at the jewelry, to take the breakfast at the restaurant and to rent her favorite movie before she wakes up.For this reason he has to to do the shortest travel possible. Be careful, only grey roads at the borders are two-way. While blue roads are one-way following arrows direction.Which is the shortest trip sequence?

AB

C

D

Puzzle 9

The shortest trip sequence is:A -> C -> D -> B -> ALook at the image to the right for path details. A

B

C

D

Puzzle 10On a tree there is a nest with ten eggs. On winter time a strong wind gust shook the nest and two eggs fell down. Furthermore during an heavy spring rain, a cracked branch fell and cracked three eggs.Assuming that no other accidents happen, how many eggs are left at the end of the summer?

Puzzle 10The right answer is 0. Because during the summer the five remaining eggs will hatch.