I know you opened your calculator app to check it.
And 299999999 is divisible by 13
Submitted 7 hours ago by m4m4m4m4@lemmy.world to science_memes@mander.xyz
https://lemmy.world/pictrs/image/1434de78-da71-47f6-9542-66fdf62c6061.jpeg
Comments
chemicalwonka@discuss.tchncs.de 44 minutes ago
TwilightKiddy@programming.dev 5 hours ago
The divisability rule for 7 is that the difference of doubled last digit of a number and the remaining part of that number is divisible by 7.
E.g. 299’999 → 29’999 - 18 = 29’981 → 2’998 - 2 = 2’996 → 299 - 12 = 287 → 28 - 14 = 14 → 14 mod 7 = 0.
It’s a very nasty divisibility rule. The one for 13 works in the same way, but instead of multiplying by 2, you multiply by 4. There are actually a couple of well-known rules for that, but these are the easiest to remember IMO.
urda@lebowski.social 4 hours ago
Thanks I hate it
veroxii@aussie.zone 1 hour ago
This math will not stand man!
darkpanda@lemmy.ca 4 hours ago
If all of the digits summed recursively reduce to a 9, then the number is divisible by 9 and also by 3.
If the difference between the sums of alternating sets digits in a number is divisible by 11, then the number itself is divisible by 11.
That’s all I can remember, but yay for math right?
TwilightKiddy@programming.dev 4 hours ago
Well, on the side of easy ones there is “if the last digit is divisible by 2, whole number is divisible by 2”. Also works for 5. And if you take last 2 digits, it works for 4. And the legendary “if it ends with 0, it’s divisible by 10”.
Usernamealreadyinuse@lemmy.world 6 hours ago
42857 for those who wonder
And for ops title: 23076923
AI_toothbrush@lemmy.zip 6 hours ago
Actually disgusting
ryannathans@aussie.zone 5 hours ago
Why
OfficerBribe@lemm.ee 4 hours ago
Never realized there are so many rules for divisibility. This post fits in this category:
Forming an alternating sum of blocks of three from right to left gives a multiple of 7
299,999 would be 999 - 299 = 700 which is divisible by 7. And if we simply swap grouped digits to 999,299, it is also divisible by 7 since 299 - 999 = -700.
Grandwolf319@sh.itjust.works 4 hours ago
49 is divisible by 7, so why not?
SerpentPeaked@lemmynsfw.com 5 hours ago
Isn’t every number divisible by 7?
ilovededyoupiggy@sh.itjust.works 5 hours ago
Yup, this is just a coordinated smear campaign from Big Integer.
Shard@lemmy.world 5 hours ago
Yes technically almost every number is divisible by another in some way and you’re left with a remainder that spans plenty of decimal places.
But common parlance when something is said to be divisible is that the end results is a round number…
henfredemars@infosec.pub 4 hours ago
…9999 is exactly equal to -1.
m_f@midwest.social 11 minutes ago
⅐ = 0.1̅4̅2̅8̅5̅7̅
The above is 42857 * 7, but you also get interesting numbers for other subsets: