Classics of Recreational Math

The classical recreational math authors are Lewis Carroll,  Henry DudleyMartin GardnerSam Loyd, and Yakov Perelman.

This an example of classical math puzzles: https://www.aplusclick.org/k/5423.htm :

(102 + 112 + 122) – (132 + 142) = ?

The picture “Mental Count” of Russian painter Nikolay Bogdanov-Belsky contains the simple calculation. Image source : Wikipedia

427px-BogdanovBelsky_UstnySchet

 

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The logic puzzle almost everyone gets wrong

This is a very famous logic problem:

“Jack is looking at Anne, but Anne is looking at George. Jack is married, but George is not. Is a married person looking at an unmarried person?

  • A: Yes
  • B: No
  • C: Cannot be determined”

married

According to the Keith E. Stanovich in Scientific American more than 80 percent of people choose C, which is not the correct answer. The correct answer is A. Why?

This is another example of a similar problem:

There are only two handshakes in a meeting: John shakes hands with a person, this person shakes hands with Anna. Does a man shake hands with a woman in the meeting?

Answer

Project Starters

Challenging puzzlers to create a positive attitude to real projects.

Everyday Geek Questions

What happens once in a minute, twice in a week and once in a year?

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I will be X years old in year X2. How old am I?

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How many planes of symmetry does a cube have?

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“1” costs $10. “20” costs $20. How much does “100” cost?

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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.

Liar’s Math

Aplusclick Pinocchio

Pinocchio lies

When Pinocchio lies, his nose gets twice as long. When he tells the truth, his nose gets 1 cm shorter.

Today, his nose was 1 cm long in the morning, and it is 100 cm long in the evening.

What is the least possible number of times he opened his mouth today?

True and Random

Two gods  are called True and Random. True always speaks truly and Random speaks randomly truly or falsely. You don’t know who is who.

Determine the identities of the gods by asking yes-no questions; each question must be put to exactly one god.aplusclickgods

Adapted from G. Boolos. ‘The hardest logic puzzle ever’, The Harvard Review of Philosophy (6), 1996.

 

You find the answers to the questions in Grade 12 questions at www.aplusclick.com

Crazy Puzzle

What number and why?Aplusclick crazy puzzle