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2026-08-08 07:26:21 +00:00 · 2023-09-29 01:02:31 +02:00 · 2023-09-29 01:01:55 +02:00 · 2023-09-29 01:00:08 +02:00 · 2023-09-29 00:59:31 +02:00 · 2023-09-29 00:58:55 +02:00
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 - [[29]] is [[drishti]] in the #Flancia [[Pattern Language]].
 - My hobby, sometimes: think about whether numbers are prime while laying down or sitting.
  - Take [[209]] -- it is not prime.
    - I find this one quite beautiful, this is how I got there:
      - It is not multiple of two or five trivially.
      - It is not a multiple of three as its digits don't add up to a multiple.
      - It is not a multiple of 7 because 210 is (as 21 is 3 * 7) and it's too near.
      - Consider the hypothesis that it is multiple of 11.
        - 220 is a multiple of 11 because 22 is.
        - 220 - 11 is 209. 
        - So 209 is a multiple of 11. What is the other factor?
      - Consider the hypothesis that it is a multiple of 19.
        - 19 * 10 is 190.
        - 190 + 19 is 209 precisely, so it is a multiple.
      - Therefore 209 is 11 * 19.
  - [[1547]] is not prime; it is 7 * 13 * 17.
    - I got to this one by whistling a 1547 tone, seeing it in [[spectroid]], then checking https://anagora.org/prime/1547 :)
Author	SHA1	Message	Date
flancian	b1bef42ad7	autopushed	2023-09-29 01:02:31 +02:00
flancian	528088508b	autopushed	2023-09-29 01:01:55 +02:00
flancian	681180ab12	autopushed	2023-09-29 01:00:08 +02:00
flancian	48a4d33665	autopushed	2023-09-29 00:59:31 +02:00
flancian	e1c1973e47	autopushed	2023-09-29 00:58:55 +02:00
flancian	960f244391	autopushed	2023-09-29 00:54:48 +02:00
flancian	c3a85f5ba1	autopushed	2023-09-29 00:54:12 +02:00
flancian	84fec223b8	autopushed	2023-09-29 00:51:50 +02:00