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?

Dream Math

Everybody dreams.

rsauter-boyThe boy dreams of being an astronaut.

How long does he need to study and work until his dream can become reality?



Which job does not require math?


The photograph courtesy of Roland Sauter


Extraordinary Math Teaching by Dan Finkel

Dan Finkel suggested principles of extraordinary math teaching:

Math can the best of time or the worst of time.



1) Start with a question.

2) Thinking happens only when you have time to struggle.

3) (Teacher), you are not the answer key.

4) Say yes to your students’ ideas.

5) Play!

A marvelous quotation is attributed to the most brilliant scientist of the modern age, Albert Einstein: “Play is the highest form of research.”




Estimate or Calculate?

” in the real world, we constantly settle for estimates, whereas mathematics — see the SAT — demands that you get the answer precisely right.” – Andrew Hacker in The New York Times article “The Wrong Way We Teach Math


boy sitting on money, money concept

Estimate or Calculate?

My answer is one of them and do it fast.

A+Click 2014 Numbers

Education by computer2014 Annual Statistics

4600+ challenging problems for students in grades one through twelve;

500,000+ sessions on websites and in 2014;

5’30” is the average duration of a session;

190 countries: USA 45%; India 9%; Canada 7%; Australia 5%; UK 5%;

10,000+ cities: top cities are  Brisbane, Australia; Chicago, USA; New Delhi, India;

25% visitors via mobile or tablets;

500 stars is the Best Score of the A+Click Challenge in 2014. Suhas, Bangalore, India is the best performer of 2014.

100 Best Performers of the A+Click Challenge in 2014: USA – 28%; Cambodia – 26%; India – 15%; Canada – 6%.

2,000+ people passed IQ Test; 454 people scored over 100;

100+ suggestions from users;

18,500 downloads of A+Click eBooks on iTunes;

A+Click continues the adventure in 2015!


SAT Math

Aplusclick has just published a new free collection of 150+ SAT Math questions at


Math Magic: To Predict Unknown


One of the math magic is to predict unknown facts. Please find below several situations where math gives unexpected and useful answers.

1. Code Testers

John detected 2 errors and Mary – 3 errors in a code. There is one error in common. How many errors are still undetected?

It looks like a joke. However there is a mathematical solution of the problem that shows that the number of undetected errors is N. I am sure that you can easily to find the number N.

99.9% fail or refuse to solve it.


2. Lake Width


How estimate the width of a lake without crossing it? You just walk and make some measures at a lakeside.


ImageFor example in the situation shown at the picture the width of the lake is 200 meters.


3. How many fish are there in the lake?

Yesterday, I caught 30 fish of a certain size in the lake.
I marked and released them without any harm.
Today I also caught and released 80 fish of the same size and noticed that there were 6 marked fish in the second catch.

How many fish of the same size are there in the lake?

4.  Seller’s decision

ImageI sell my car. People come to my garage one at a time and make bids to buy it. I make an immediate decision whether to accept or reject an offer after receiving it. I decide to reject the first N offers, mark the highest price P, and accept the first offer that is greater than P.

What number N do you recommend me if I expect that 100 people can make a bid?

If N is small, I can accept a small amount of money.
If N is large, I can reject the best offer.

This is the famous problem of the optimal stopping theory (Secretary Problem).

5. Winning Strategy

In a game, Anna and Bill take 1, 2, or 3 coins on each turn. The player to take the last coin from the pile wins. If Anna goes first and there are 40 coins on the table, how many coins should she take to guarantee that she would win?

The truth is “She always loses if Bill knows the winning strategy.” Do you know Bill’s strategy?