this post was submitted on 18 Oct 2024
623 points (95.1% liked)
Curated Tumblr
4051 readers
313 users here now
For preserving the least toxic and most culturally relevant Tumblr heritage posts.
Image descriptions and plain text captions of written content are expected of all screenshots. Here are some image text extractors (I looked these up quick and will gladly take FOSS recommendations):
-web
-iOS
Please begin copied raw text posts (lacking a screenshot that makes it apparent it is from Tumblr) with:
# This has been reposted here to Lemmy as part of the "Curated Tumblr Project."
I made the icon using multiple creative commons svg resources, the banner is this.
founded 2 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
9 plus a number? No. 10 plus a number, minus 1. Yis.
I just memorized any addition with 9 adds a 1 in front while reducing the other number by one. Same general step, but there's no 10 in my head, just 9+7 -> 16. Basically, promote the tens column while demoting the ones column. I think of it more like a mechanical scoreboard (flip one up, flip the other down) than an operation involving a 10.
If it's anything other than 9, I fall back to rote memorization, unless the number is big, in which case I'll do the rounding to a multiple/power of 10.
Yeah that's a more accurate description of what i actually do in my head to. I'm not "adding 10", because I already would use a short hand method for adding 10 anyway to promoting the tens place or flipping the score card, as you said.