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#526 Re: Maths Is Fun - Suggestions and Comments » Prime Numbers - Advanced » 2006-05-15 19:41:11
Well, I just thought those topics kind of linked...
So, you wanted some ideas 
:
Amicable numbers - where the sum of one numbers factors is equal to another number, and vice versa.
Sociable groups - this is the same as amicable numbers but with 3, 4, 5 or more! The 'order' of a sociable group is how many number are in the sequence. So, perfect numbers are of order-1, sociable groups of order-2 are amicable numbers. But, no groups of order-3 have been found yet. There are, however, many groups of 4, 5 etc.
Smallest group of order-4
1264460, 1547860, 1727636, 1305184
Of order-5:
12496, 14288, 15472, 14536, 14264
Aliquot sequences - every number has its own Aliquot sequence, and lots of Aliquot sequences are the same - they just start in different places. To find a number's Aliquot sequence first add its proper factors (all positive factors excluding the number itself):
20 has proper factors 1, 2, 4, 5, 10, which add to make 22
22 has proper factors 1, 2, 11 which add to make 14
14 has proper factors 1, 2, 7 which add to make 10
10 has proper factors 1, 2, 5 which add to make 7
7 has proper factors 1 which add to make 1
1 has no proper factors, which add to make 0
0 has no proper factors, which add to make 0 ...
An Aliquot sequence terminates when it reaches a number already found (forming a sociable group) or when 1 is reached, because the next number will automatically be zero.
A perfect number's aliquot sequence consists only of itself.
A prime number's aliquot sequence consists of itself and 1.
An amicable number's aliquot sequence consists of itself and its amicable partner...
There are also Aliquot sequences that go forever (at least, nobody knows when they will stop)!
#527 Re: Guestbook » How can I insert a picture? » 2006-05-14 19:12:54
To insert a picture?
Okay, first of all find an image on on the internet. Copy its URL (like, http://www.mathsisfun.com/images/dog-pointing.gif).
Then, put image tags around it:
[img]insert website here[/img]
That's all!
Or, if your picture is saved on your computer, you can upload the picture by clicking 'Post Reply' and then using 'Image Upload'. It must be a .gif, .jpg or .png file though and must be less than 1501x1501 pixels and 100 KB.
#528 Re: Maths Teaching Resources » Papers (C1-4, M1-6M S1-6, D1-2, AEA) QP+MS » 2006-05-13 12:26:44
Thanks.
Topic moved from 'Help Me' --->
#529 Re: Maths Is Fun - Suggestions and Comments » Prime Numbers - Advanced » 2006-05-11 19:29:48
Excellent!
Advanced is blue!
Maybe you could go on from amicable numbers to have topics on sociable groups and Aliquot sequences?
#530 Re: Dark Discussions at Cafe Infinity » We're surrounded by morons.. » 2006-05-10 19:53:54
that site also holds records in digits of √2 and e
And also both while juggling! That is cool.
All these stories about memorising things reminds me of an old movie I saw ages and ages ago. I can't really remember much, but there is a guy who is a bit of a genius and one of his talents is knowing the phonebook back to front. When he meets people he already knows their phone number.
#531 Re: Puzzles and Games » 100 is fun! » 2006-05-10 19:28:27
He loves the png.
#532 Re: Guestbook » games » 2006-05-09 22:49:23
This has got nothing to do with anything, but I've only just noticed there is a Games 4 page!
But, Games 4 page is only accessible from the Games 1 page - when you go to Games 2 or 3 pages the link disappears (fix, yes?).
#533 Re: Dark Discussions at Cafe Infinity » We're surrounded by morons.. » 2006-05-09 22:40:48
That list is amazing. Imagine actually spending time to learn the whole thing.
#534 Re: Maths Is Fun - Suggestions and Comments » Sudoku » 2006-05-09 21:29:53
Yay! Sudoku! It's great!
Some problems/suggestions:
* An easier-to-read font (for the numbers especially). I misread threes for eights and vice versa.
* When I tried to build an Advanced Hard (also, is there a better way to phrase this level?) grid each number loaded one by one at about a rate of one number per second. And my browser window started responding very slooooowly.
* The MathsIsFun.com home link doesn't work.
#535 Re: Introductions » A new guy » 2006-05-06 14:23:05
strange half-sentences like these on them.
#536 Re: Introductions » hello =) » 2006-05-06 14:20:58
I'm a bit late, but hi, numen!
By the way, I thought your avatar was cute.
#537 Re: Puzzles and Games » Nerd Search » 2006-05-06 14:18:29
Hey, that's awesome!
Maybe I coulod adapt this game to suit: http://www.mathsisfun.com/games/word-search/
Yes!
You could have separate nerdsearches using different types of clues to figure out the numbers - starting easy (subtraction, multiplication), and then getting harder (trigonometry, factorising/expanding, surds etc etc.)
#538 Re: Jokes » More clean jokes :) » 2006-04-23 20:38:35
#539 Re: Maths Is Fun - Suggestions and Comments » Quincunx » 2006-04-21 18:24:42
It is pretty cool to watch - needs a good backing track!
I know - the Hex Drums!
#540 Re: Maths Is Fun - Suggestions and Comments » Quincunx » 2006-04-20 23:30:14
It's hypnotic to watch! I can stare at it for hours! 
Photo: my test run. The units column of numbers got chopped off!
#541 Re: Maths Is Fun - Suggestions and Comments » Minesweeper MathsIsFun Style » 2006-04-20 21:05:38
Incidentally, I found this on the internet a while ago. It's the same idea as minesweeper, but 3D!
Edit: I just realised the instructions on that page are in Japanese.
Mission completion!!
I like it.
#542 Re: Introductions » hi say wot u fink of maths » 2006-04-19 23:22:18
i have been a maths for sixteen years and i am very offended by this topic.
I'm even offended by his grammer and I hate grammer!
Teehee.
#543 Re: Guestbook » Shout Out!!!!! Very Important!!!!!! » 2006-04-16 12:51:14
They certainly do.
Good luck, best wishes and congratumalations jU!
#544 Re: Maths Is Fun - Suggestions and Comments » Hex Drums » 2006-04-05 20:03:57
This is fun! Thanks Rod!
90A0C01A1842D182
On the Binary, Decimal and Hexadecimal Numbers page, in the 'Counting' flash window, the white bits on the play button aren't transparent, whereas the pause button is. Purely for looks...
The Hexadecimal number are interesting.
Maybe insert an 's' or rephrase the sentence? That's all. Thanks.
#545 Re: Dark Discussions at Cafe Infinity » The Cure for Information Overload » 2006-04-04 20:16:28
There is no end (I checked!). It loops back.
#546 Re: Maths Is Fun - Suggestions and Comments » Hex Drums » 2006-04-01 10:44:45
Now I just need some more ideas ...
A speed adjusting slider, for changing the tempo?
Oh, yes, I like the random idea.
One more thing: when I click on the 'hex drums' title in the flash page, I get this message:
Oops! - can't find the file "/games/hexadecimal-drum-machine.html"
#547 Re: Maths Is Fun - Suggestions and Comments » Hex Drums » 2006-03-31 20:07:12
Wow! It's cool! I'm going to have a play!
Do you remember when a guest once posted asking for 'maths music games' and we had no idea what that meant? Well, I think this qualifies!
#548 Re: Guestbook » maths » 2006-03-30 18:36:54
, to you too.
#549 Re: Guestbook » hi » 2006-03-30 18:33:14
The western hemisphere
And the northern hemisphere?
#550 Re: Guestbook » hi » 2006-03-30 18:31:42
How can you think it isn't?