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Volkomen Kwadraten en Irrationale Getallen
Een irrationaal getal is een reëel dat niet kan geschreven worden als a/b met a ∈ ℤ (een geheel getal) en b ∈ ℤ0 (een natuurlijk getal). Een getal is een volkomen kwadraat als het het kwadraat is van een geheel getal. Een paar voorbeelden zijn 1, 4, 16 etcetera. Een ‘interessante’ eigenschap van volkomen kwadraten is dat ze altijd eindigen op een even aantal nullen (geen nul is ook een even aantal). Je kan dit inzien door naar de kwadraten van 1 tot 10 te bekijken die allemaal niet op een nul eindigen behalve 102 dat eindigt op 2…
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Perfect Squares & Irrational Numbers
An irrational number is a real number that cannot written in the form a/b with a ∈ ℤ (a whole number) and b ∈ ℤ0 (a natural number or whole number excluding 0). A number is a perfect square if it is the square of a whole number. A few examples are 1, 4, 16 etcetera. One ‘interesting’ property of perfect squares is that they always end with an even number of zero’s (no zero is also an even number of zero’s). You can see this is true by looking at the squares of 1 to 10 which all end…
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Wondrous Arithmetic
Here at home we just had exams again and I helped my daughter preparing for her math exam. We started doing this during the 2020 lock down and we have continued since then. Surprisingly enough I still know most of the math I got in high school more than 30 years ago. This is in stark contrast with other subjects like chemistry which I have mostly forgotten. This time one of the exam topics was trigonometry and during preparation I solved a problem coming to an answer that was different from the one given at the back of the book.…
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Wonderbaarlijk rekenen
Het waren weer examens en ik heb mijn dochter wat geholpen bij de voorbereiding van haar wiskunde examen. We zijn daar mee begonnen tijdens de lockdown van 2020 en ze had er blijkbaar iets aan dus doen we zo voort tot ze het niet meer nodig vindt. Het was verrassend voor mij dat ik na 35 jaar die wiskunde zelf nog allemaal in mijn hoofd had zitten. Hier en daar moet ik wel eens iets opzoeken en de formules ken ik niet meer van buiten maar verder zit het er nog in. Dit in scherpe tegenstelling tot bijvoorbeeld wiskunde waar…
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Genius. The Life and Science of Richard Feynman, James Gleick (ISBN 978-0679747048, Vintage)
After having reread the collected Feynman anecdotes from Surely You’re Joking and What do you care ? in the Classic Feynman edition I wanted to reread this biography by James Gleick again. The main reason being that the anecdotes focus on stories that happened to Feynman leaving out most of the science. Originally I read the stories again because I wanted to give them to my daughter to read as an unorthodox introduction in physics. But they are really ‘just‘ stories from a curious character as the byline in the title suggests. They are often funny, surprising and exceptional but…
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Fist of Fury
The second movie starring Bruce Lee. This is a classical story in the martial arts movie genre with a Chinese hero fighting for the honour of the Chinese agains foreign oppression and aggression. A superior Chinese martial artist is murdered after being poisoned by the Japanese. All typical Bruce Lee movie elements appear again with the noises, blood tasting and bare chested fighting. Compared to ‘The Big Boss’ the story is better this time as it is a classical storyline with the good Chinese against the bad Japanese oppressors. Many actors from the big boss return including James Tien, Nora…
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The Big Boss
I recently watched ‘The Big Boss’ again with my son. This movie from 1971 start Bruce Lee in his first major film role as the leading star. It is vintage Bruce Lee, including extreme close ups of his face, grimacing, the tasting of blood before he really unleashes his devils, the howling sounds he makes and of course the lightning fast kicks and punches in fight sequences with Bruce Lee bare chested against dozens of adversaries. At the start we see Lee going into ‘hiding’ in Thailand to get away from the fights he keeps getting into at home. Although…
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Apollo 13
This movie with Tom Hanks playing Jim Lovell came out in 1995. It is about the disastrous Apollo 13 flight and based on the book ‘Lost Moon’ by Jim Lovell. Apollo 13 was the third flight scheduled to land on the moon and so got little prior attention from the press. That changed dramatically after an oxygen tank exploded on the spacecraft on the way to the moon. Instead of landing on the moon the three astronauts and ground control have only one objective left which is to bring the astronauts back safely to Earth. The movie largely depicts the…
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Harry Potter and the Prisoner of Azkaban, J.K. Rowling (ISBN 978-1408855676, Bloomsbury)
The third Harry Potter book. As you probably know each Potter book follows Harry during a year at Hogwarts school of Magic. So, in book 1 he was 11 years old and going to his first year. In The Prisoner of Azkaban we meet Harry during the summer at his uncle and aunt awaiting the third school year at Hogwarts. As Harry grows older the story evolves with him. Where the first 2 books were light and mainly humorous in tone, things start to turn dark in book number 3. Summers at his uncle and aunt are always a torment…
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File extensions
Ever wonder where these (mostly) 3 letter file extensions come from ? Here are 14 common ones : .bat : batch .bmp : bitmap .cfg : configuration .doc : document .exe : executable .flac : free lossless audio codec .gif : graphics interchange format .jpg : joint photographic experts group .nfo : information .png : portable network graphics .ppt : powerpoint .tmp : temporary .txt : text .wav : wave
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