Posted in Curiosity, For the whole family, geometry, Uncategorized by: admin

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18 Nov

TweetIn the previous blog I described a discovery of Hirotaka Ebisui and an observation by Thanos Kalogerakis, both concerning what's known as Vecten's configuration. Vecten's configuration is a generalization of the famous Bride's Chair that underlies Euclid I.47, generally identified as the proof of the Pythagorean Theorem, although by now there are hundreds of them. […]

Posted in Arithmetic, Books to read, For the whole family, math fun, Mental arithmetic by: admin

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01 Apr

I strongly believe that those tricks are more than anything else convey to the early learners the essence of practicing mathematics. Presh Talwalkar's book may also open the eyes of an older generation on what they missed in the early grades.

Posted in A must read, About math, About mathematicians, Applications, For the whole family, History by: admin

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06 Jul

But naturally, mathematics was not evolving all by itself. The authors excel in presenting establishment of the science of meteorology as a human endeavor. The history of meteorology is rich in perseverance, sacrifice, enthusiasm, ingenuity, useful missteps, multinational collaboration ... and plain hard work. Authors' fluent recount makes the story all the more fascinating, even if math applications are only at the back of your mind. The book is a superior read.

Posted in Books to read, For the whole family, History, physics by: admin

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14 Feb

I realize that the book was shipped some time before the tweeter discussion has started; still, the thought that there might be a relation to the butterfly effect crossed my mind. On opening the book I almost immediately noticed a cartoon that did not immediately invoke any connection to weather prediction

Posted in Algorithms, Curiosity, For the whole family, Games, Homeschooling by: admin

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19 Sep

I believe that the discrete variant makes the solution more transparent. For example, think of coffee and cream not as liquids but as collections of molecules. Since the number of molecules in the two glasses remains the same even after repeated iterations, cream molecules in the "water" glass come at the expenses of the water molecules in the "cream" glass and, therefore, the two quantities are equal.

Posted in Algorithms, For the whole family, geometry by: admin

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02 Aug

TweetIn grades 1 through 5, my little boy went to a private Hebrew school. Every day I drove him there and then picked him up at the end of the day - half an hour drive each way. We spent the combined hour mostly talking of mathematics. For the next three years he took the […]

Posted in Curiosity, For the whole family, math fun by: admin

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27 Jun

There are 31 bags placed in a row with 100 identical coins each. One bag is selected and one coin is moved from the selected bag to every bag to the right of it. A question can be asked for a total number of coins in any group of bags. How many questions are needed to determine the chosen bag?

Posted in About math, About mathematicians, Books to read, For the whole family by: admin

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16 Jun

TweetI like buying books, especially serendipitously. For the past year this was mostly by simply browsing the amazon.com Kindle store. Today after a long hiatus I bought a book in a bookstore of old ("conventional" may not be the right word anymore.) I've been taking a walk with my sister-in-law - a full-time Israeli, and […]

Posted in A must read, Books to read, Education reform, For the whole family, How children learn by: admin

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24 Feb

I always feel apprehension on seeing the number line or x-axis introduced as a horizontal line, with the numbers increasing left to right. When the time comes, the y-axis is commonly introduced as perpendicular to the x-axis and hence vertical. Seldom there is enough time for a trifle observation that the direction of a number line is irrelevant and that the choice of the orientation of the system of axes in the plane is a matter of convenience. The trouble comes when there is a need to change variables or, say, introduce the inverse function.