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?

Fermi Problem

Often, a problem solver might estimate the required value without very much information. He/she might aim to get an order of magnitude estimate. The estimation technique is named after physicist Enrico Fermi, as he was known for his ability to make good approximate calculations with little or no actual data. Fermi problems typically involve making justified guesses about quantities and their variance or lower and upper bounds.

The classic Fermi problem, generally attributed to Fermi, is “How many piano tuners are there in Chicago?” – Wikipedia

Several simple examples of Aplusclick Fermi problems:

Lightening Strike  Lightnings over lake Balaton

Tennis Balls in a Bus

English Language Words


Lady’s Age

Security Control

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


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.

Coin Landing On Its Edge

I flip a fair Swiss franc* and it falls in mousse**. What is the probability that the coin stays on its edge after the mousse melts? 
*One Swiss franc is about 1 USD; diameter 23.20mm , thickness 1.55mm, weight 4.4g.  During a coin toss, the coin is thrown into the air such that it rotates edge-over-edge several times.
**A mousse (French ‘foam’) is a prepared food that incorporates air bubbles to give it a light and airy texture.


The probability  that the coin stays on its edge is about 4% for a Swiss franc and 5% for an American dime.

Such an outcome on a hard and flat surface is fairly unlikely, having been estimated at approximately 1 in 6000 tosses.



What is digital fluency?

Source: What is digital fluency?

The Importance of Recreational Math

“The body of recreational mathematics that Mr. Gardner tended to and augmented is a valuable resource for mankind.” –

Aplusclick project tries to destroy the border between the Common Core and the Recreational Math.