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R E K

In the book The Design of Everyday Things, Don Norman talks about what he calls "Good Enough Arithmetics", which is a way of calculating results in your head when precision isn't important. The approximate answer is often good enough.

I gathered a few notes on my website as a reminder, and plan to add more as I find them :neofox_book:

kokorobot.ca/site/good_enough_

9 September at 18:03 | Open on merveilles.town
22 comments
Drew Breunig

@rek I enjoyed that book and really enjoyed that I happened to follow it up with this: lostartpress.com/collections/d

9 September at 18:06 | Open on note.computer
.CLI

@rek I love this! Something adjacent I've been trying to memorize lately is "good enough time zone conversion" - knowing roughly what time is it at places I care about

9 September at 18:10 | Open on merveilles.town
cerement

@rek

there’s a whole series of quick checks for divisibility:
- number ends in even digit = divisible by 2
- number ends in 0 or 5 = divisible by 5
- digits add up to multiple of 3 = divisible by 3 (ex. 54 → 5+4 = 9)
- digits add up to 9 = divisible by 9
- (from 11 to 99) doubled digits = divisible by 11

ex. 66
- doubled digits = divisible by 11
- ends in even digit = divisible by 2
- 6+6=12, 1+2=3 = divisible by 3
- and then working backwards, 66 is also divisible by 6, 22, and 33

@rek

there’s a whole series of quick checks for divisibility:
- number ends in even digit = divisible by 2
- number ends in 0 or 5 = divisible by 5
- digits add up to multiple of 3 = divisible by 3 (ex. 54 → 5+4 = 9)
- digits add up to 9 = divisible by 9
- (from 11 to 99) doubled digits = divisible by 11

9 September at 18:33 | Open on social.targaryen.house
Sorĉist'! (Ed H) :flago:
Marcus Rohrmoser 🌻
poetaster
Avi Bryant

@rek some rough conversions I use pretty frequently:
1m = 39”
6mm = 1/4”
1m/s = 2kts
60mph = 100km/h
1 day = 100,000 seconds

9 September at 19:48 | Open on cosocial.ca
R E K

Fun with ASCII 🖐️ 👈 🤟
10 September at 20:39 | Open on merveilles.town
R E K
𝐩fᵣ

@rek I live in Australia (it still gets cold here!) and I am absolutely wearing a jumper (that's what we call sweaters) if it's under 20 Degrees Celsius.

11 September at 0:06 | Open on social.sdf.org
Kevin Boyd
Tagomago

@rek You’re so brave to lay out inline graphics and text like that 😁

11 September at 6:49 | Open on mastodon.social
R E K

@tagomago why brave? Dare I ask? :neofox_confused:

11 September at 14:42 | Open on merveilles.town
Tagomago

@rek Because any change on the character count of any line breaks the graphic, I reckon? :thonking:

11 September at 19:16 | Open on mastodon.social
R E K

@tagomago it won’t break cause it’s wrapped in a <pre> tag :P

11 September at 19:18 | Open on merveilles.town
Tagomago
R E K

@tagomago although on a small screen it might mean having to scroll to the right to see it in its entirety ^^; (pre area has a horizontal scroll bar on small screens)

11 September at 19:21 | Open on merveilles.town
Ed Davies
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