## Is Zero Your Hero?

June 9, 2018 Leave a comment

Everybody has a favorite number. What number is your hero?

Math and Logic Puzzles

June 9, 2018 Leave a comment

Everybody has a favorite number. What number is your hero?

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April 18, 2018 Leave a comment

Grow your passion by motivating practice like the 11-year-old Math Marvel

“Chess is a mathematical poem” – *Aarushi Maheshwari *

May 7, 2017 Leave a comment

Why we frequently use number 7?

Why there are seven days of week? seven deadly sins? seven wonders? . . . .

Look for the answer in the night sky or at aplusclick.org

December 10, 2016 Leave a comment

The top OECD countries were **Singapore**, **Japan**, **Estonia**, **Finland** and **Canada**. These countries also achieve high levels of performance and equity in education outcomes.

Source: OCDE

More than one in four students in Beijing-Shanghai-Jiangsu-Guangdong (China), Hong Kong (China), Singapore and Chinese Taipei are top-performing students in mathematics, a higher share than anywhere else.

Students in larger schools score higher in science and are more likely than students in smaller schools. Students in smaller schools reported a better disciplinary climate.

Gender gap: the share of top performers in science is larger among boys than among girls. Finland is the only country in which girls are more likely to be top performers than boys. Girls mostly seek positions in the health sector and boys in becoming ICT professionals, scientists or engineers.

Five sample PISA Math questions:

December 9, 2012 1 Comment

When required to make a decision, I have the option to produce simple calculations, guess, or even refuse to decide. What is better?

The answer depends on many circumstances, including:

- Complexity of the challenge.
- Usefulness of the conclusion.
- Individual ability / habits to analyze challenges.
- Time available.

I meet difficult challenges very often. What technique should I use? Should I work it out or should I guess?

Calculations are beneficial in terms of time and money in the following examples:

I am ready to spend my time on simple analysis and calculation in such cases.

Weinstein and Adam [1] advise **guesstimating** certain categories of challenges. A guesstimate is an informal English contraction of guess and estimate and is used to describe an estimate made without complete information. Another term for this is an educated guess at something for which no better information will become available.

There are a group of challenges called “Fermi problems” (after the great nuclear physicist) that will be accurate to within an order of magnitude. A mistake up to 10 times is acceptable. The examples are:

- How many people will potentially buy a new car next year in a city?
- How many gas stations between Boston and New York?
- How many people will come to buy my car if I advertize on the Internet?
- How many tennis balls can fit in a school bus?
- What score does John expect to receive on the exam?
- How long is Anna’s hair?
- How many times heavier than a rabbit is an elephant?
- How many customers visit a shop everyday?

I need to guesstimate in order to answer such questions.

The answer to the question in the title “Calculate or Guess?” is yes. I calculate when I have time and the ability, I guesstimate when a conclusion with order of magnitude is acceptable, and I trust my gut feeling in all other cases.

*1. *Lawrence Weinstein and John A. Adam,* Guesstimation: Solving the World’s Problems on the Back of a Cocktail Napkin. *2008 Princeton University Press. ISBN 9780691129495