## Car Owner’s Puzzles

Can a specific subject provokes interest to Math?

For example, cars. How much does the gas cost in a month? What speed to choose? When do I need to change the tires? How to be on time? How much do I pay for a car during its life? . . .

What are other intersting subjects? Finance? Love? Sport?

## How to Solve a Problem – Read the Question

Try to solve the following problem suggested by Leslie Green:

What is the difference between the number of letters in UPPER CASE and lower case in the text?

Most of the people and me too answered the question fast: None.

The trivial advice is often useful: “Try to answer exactly to the question.”

Do you get another answer? What is it?

## Geek’s Questions: The Art of Asking Yourself

A+Click contributor Gerry Geek just published a new true story:

A group of friends visit me. They eat and drink everything, even the cat’s food, and then leave. The fridge is empty – only a glass of milk is left. I give half of the milk to my cat Ben. He drinks half of it and then I drink half of what is left. Again, he drinks half of what is left and then I do the same. We continue until nothing is left. What proportion of the initial amount of milk did I drink in total?

I remember the moment when I saw Jane for the first time. We were sitting at the same table at a tea room along with Mary and John. We looked at each other and I was sure that everybody immediately chooses another. If two boys and two girls choose a partner, then what is the probability that everybody chooses the person who chooses them?

Before I met Jane I had a relationship with three girls who lived in the same house. I sent three letters to them. If the postman put the letters into three different boxes without looking at the name of the recipient, what would be the probability that all girls received their letters?

## The man who counted

The man who counted

“In 1932 Malba Tahan published what would became one of the most successful books ever written in Brazil – O Homem que Calculava – The Man Who Counted.”

## Really Practical Math

Math can be really practical and useful!

For students.

For lock breakers.

For car racers.

For pool managers.

For family folks.

## Funny Logic : Serious Math

Math is fun. Ten sample problems prove that math and logic can be interesting. It provides a link to collection of challenging math and logic puzzles.

Can be Math Funny? Try to solve 10 problems from A+Click.

## You Are A Math Genius!

Everybody was born a genius! You too!

Unleash the genius that sleeps within.

One of the possibilities is a small everyday dose of brain work.

Look at the puzzle below.

At the beginning, it can drive you crazy.

Don’t give up!

Take an easier challenge and GROW!

Aplusclick provides you with an enormous opportunity for everyday training!

You start with unpractical number puzzles and finish by solving practical optimization problems such as finding the shortest underground route …

… or packing the maximum possible number of boxes in a room.

Remember: You are a genius! Don’t miss an opportunity to grow!

A rendezvous at www.aplusclick.org

## Beautiful Math Problems

What are characteristics of the most beautiful math problems?

They are practical, they give an impression that the problem cannot be solved, and finish by an unexpected (surprise) solution.

It is not about the beautiful math equations or mathematical beauty. It is mostly about recreational math, brain teasers, and thinking outside the box.

Find a short list of my favourite beautiful problems:

1. Morozkin’s problem:

Vladimir Arnold (1937-2010), one of the greatest 20th century Russian mathematicians told the following story:

“Our schoolteacher I. V. Morozkin gave us the following problem: Two old women started at sunrise and each walked at a constant (different) velocity. One went from A to B and the other from B to A. They met at noon and, continuing with no stop, arrived respectively at B at 4 p.m. and at A at 9 p.m.  At what time was the sunrise on this day?”

Solution

2. Martin Gardner’s favorite problem

“Three sailors come across a pile of coconuts. The first sailor takes half of them plus half a coconut. The second sailor takes half of what is left, plus half a coconut. The third sailor also takes half of what remains, plus half a coconut. Left over is exactly one coconut, which they toss to a monkey. How many coconuts were in the original pile?”

Solution

3. Lucas problem

François Édouard Anatole Lucas (1842 – 1891) was a French mathematician.

Every day at noon, a ship leave Le Havre for New York and another ship leaves New York for Le Havre. The trip lasts 7 days and 7 nights. How many ships will a ship leaving Le Havre today meet at sea?

Solution

4. Euler bridge problem

In a city Konigsberg, there were seven bridges. There was a tradition to walk and cross over each of the seven bridges only once. If a person starts and finishes at the same point, can he accomplish this task?

Solution

5. Secretary problem

An entrepreneur wants to hire the best person for a position. He makes a decision immediately after the interview. Once rejected, an applicant cannot be recalled. He interviews N randomly chosen people out of 100 applicants, rejects them and records the best score S. After that, he continues to interview others and stops when the person has a score better than S. What number N do you recommend to the cruel man?

Solution

6. Monty Hall

A venture capitalist will invest in only one of three start-up companies: A, B, or C. I will make a lot of money if I invest in the same company, and will lose all of my money if I choose another company. I decide to invest in company A and I inform the venture capitalist. He assures me that he does not invest in company C. What company do you recommend for me to make the investment?

Solution

7. The Legend of Carthage

The Legend of Carthage: Queen Dido and her followers arrived in North Africa. The locals told them that they could have the coastal area that an ox hide would cover. She cut the hide into a series of thin strips, jointed them together, and formed a coastal shape. The ox-hide enclosed area was known as Carthage. If you had a 10 km long strip, which shape (rectangle, triangle, semi-circle, or semi-ellipse) would you choose to maximize the enclosed area?

Solution

8. Lewis Carroll’s Coaches

A coach leaves London for York and another at the same moment leaves York for London. They go at uniform rates, one faster than the other. After meeting and passing, one requires sixteen hours and the other nine hours to complete the journey. What total time does each coach require for the whole journey?

Solution

You are welcome to expand the list by submitting your input at the website www.aplusclick.org

## Why choose Math at A+Click?

Practice is the best way to develop math skills, special thinking, and logical reasoning.

More than 271 million pages are returned for the keyword search “puzzle” on Google. Furthermore, tons of pages, books, and games include puzzles, questions, and problems. Which one do you choose?

Many students choose A+Click. Why? What distinguishes A+Click from other web pages? Below is the answer:

1) It has interesting, diverse questions

2) Everything is simple and visible

3) It has international competitions, statistics, and certificates

4) Everybody can have a go, even adults

5) It works on all computers, tablets, iPads, iPods, and smartphones

6) It offers endless problems (3600+ questions)

7) No charge

Certainly, we can easily find sites or books with some of these features. A+Click distinguishes itself from others by collecting all of them together. It unites the expertise of dozens of experts such as math teachers, puzzlers, logicians, and curious people in one of the simplest forms available.

“I am always ready to learn although I do not always like being taught.” – W.Churchill.   A+Click does not teach, it gives an opportunity to learn.

Learning is doing, not watching. Learning is active, not passive.

The A+Click team hopes you will find the collection interesting and useful. Try it at https://www.aplusclick.org

## Brain Teaser Interview Questions and Answers

Brain Teaser Interview Questions and Answers

answers brain teaser interview questions that are commonly asked at job interviews for technical and quantitative roles. These questions focus on problem solving, spatial reasoning, and understanding.

By reading this document, you’ll be better prepared to answer unexpected questions, think outside the box, and elaborate on non-standard solutions. And most importantly, you’ll be calm and relaxed at the interview.

Answers to  brain teaser interview questions including:

• How do you find your car along a very long street when you don’t remember where you parked it?
• We want to merge 4 companies into one large company. How many ways are there to merge them?
• I have a rectangular piece of cheese with a round hole. How do I cut the piece with one straight lien into two parts of equal weight?
• There are a number of stones, all of different weights. The 10 lightest stones weigh 40% of the total weight. The 5 heaviest stones weigh 25% of the total weight. How many stones are there?
• What is the avg. of the smaller of three random numbers of 0 to 1?
• “1” costs \$10. “20” costs \$20. How much does “100” cost?
• It takes 6 people 48 hours to paint a house. How long would it take to paint the house if 3 people were added to the middle of the project?
• 3 apples were weighed in pairs and the weights were 200, 204, 208 grams. What is the weight of the lightest apple?
• You are shrunk so that your height is equal to the diameter of a dime (a ten-cent coin) and your mass is proportional reduced so as to maintain your original density. Who is heavier, you or the dime?
• I roll two dice. What is the probability that the 2nd number is greater than the 1st?