Quod Erat Demonstrandum

2009/06/18

閒談小學數

Filed under: Family,Fun,mathematics — johnmayhk @ 6:50 下午
Tags:

一。完美數

二。順序素數

同學也曾聽聞 x^2 + x + 41 是所謂「質數製造機」吧(代入 x = -40, -39, \dots , 38, 39 得出的值全是素數),這裡多介紹四個:

6x^2 + 6x + 31 (代入 x = 0, 1, \dots , 28)
2x^2 + 29 (代入 x = -28, -27, \dots , 28)
x^2 - 79x + 1601 (代入 x = 0, 1, \dots , 79)
x^2 - 2999x + 2248541 (代入 x = 1460, 1461, \dots , 1539)

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A good site for learning English, students, you may find it useful:

http://www.natcorp.ox.ac.uk/

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阿仔預祝做爸爸的看倌:父親節快樂

歌詞

我有我有一個好*爸爸,
每天每天都好想見到他;
日日夜夜陪住佢,
攬o下錫o下好爸爸,
爸爸呀好爸爸呀。

*爸爸 can be replaced by 媽媽 or something else…

8 則迴響 »

  1. 呀sir~點樣用依個方法整45個digit既素數

    迴響 由 Carmen — 2009/06/18 @ 8:44 下午 | 回覆

  2. 123456789 is NOT a prime, hence, if we create a number with 45 digits (or 9n digits in general) in the same way, it MUST NOT be a prime.

    迴響 由 johnmayhk — 2009/06/18 @ 10:06 下午 | 回覆

  3. John sir,
    請問聖芳濟下年(09~10)會用咩Pure Maths書呢?
    人地話係Breakthrough Pure Mathematics, 但係用邊個Edition?

    迴響 由 Wong Yat Pang — 2009/06/20 @ 12:03 下午 | 回覆

  4. 1. 在這裡說好像有點賣廣告…
    2. 沒有聽盛 sir 說要轉書,如無意外和已往的一樣吧。

    迴響 由 johnmayhk — 2009/06/20 @ 4:07 下午 | 回覆

  5. John Sir, do you have any primary 3-5 funny mathematics topics introduce to me? I have to organize two classes, each lasts for 60 mins. If you have any books or websites introduce to me, please forward it to me and thousand thanks to your help.

    迴響 由 Titus — 2009/06/25 @ 4:35 下午 | 回覆

  6. Firstly, just give you the following famous site in TW:

    http://www.mathland.idv.tw/fun/fun.htm

    迴響 由 johnmayhk — 2009/06/25 @ 9:43 下午 | 回覆

    • Thank you so much John Sir~
      This is really useful to my program~
      Thanks again~

      迴響 由 Titus — 2009/06/26 @ 10:53 上午 | 回覆

      • It is very interesting to teach primary school students about mathematics, I used to teach a primary school summer class, the responses from students were very encouraging! Titus, feel free to ask me if you want to.

        迴響 由 johnmayhk — 2009/06/26 @ 11:26 上午


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