I invented a new math formula, I'm so smrt.

[K.I.L.E.R]

I'm doing lists and logic in maths.
So I'm reading about subsets and their combinations.

S = {a, b, c}

Subsets are:
{}, {a}, {b}, {c}, {ab}, {ac}, {bc}, {a, b, c}

So I figure, who wants to count combinations?
Why not factorialise this?

S = {a, b, c}, count conversion {1st element, 2nd element, 3rd element}

countS = e! + 2
The "+2" comes from the null set and the total number of elements.

I know how to apply math. Isn't this cool?
Next time I'll brag about knowing the alphabet.

 

[K.I.L.E.R]

Whoops! I think I made a booboo.

I've just read the next line in the book and it says the total elements a set has is 2^n, where 'n' is the number of elements inside the set.

I was doing combinations of sets.
I forgot the no. 1 rule of sets, sets have unique elements.

Whoops, I think I should read the chapter before doing all sorts of nasty things to the math.

i lkie teh nasty11!!!11

 

[Guden Oden]

You know what's REALLY depressing, Kruno?

You see, there probably was some arab or chinese who did the EXACT SAME boo-boo you did in the eighth century or so, thinking he'd discovered something but hadn't.

 

[TekkenMaster]

You know what's REALLY depressing, Kruno?

You see, there probably was some arab or chinese who did the EXACT SAME boo-boo you did in the eighth century or so, thinking he'd discovered something but hadn't.

I don't know about Arabs but the Chinese that I know are crazy at everything maths. They have difficulty explaining it and helping me to understand but they can do it anyways. Weird.

 

[Sage]

did you know that you can add the digits of a number and then divide that number by 3 and the resulting decimal will be the same as the decimal on the original number?

for instance, take the number 567321964...

5 + 6 + 7 + 3 + 2 + 1 + 9 + 6 + 4 = 43
4 + 3 = 7
7 / 3 = 2.333
567321964 / 3 = 189107321.333

56431...
5 + 6 + 4 + 3 + 2 = 19
1 + 9 = 10
10 = 1
1 / 3 = 0.333
56431 / 3 = 18810.333

68352...
6 + 8 + 5 + 2 = 24
2 + 4 = 6
6 / 3 = 2.0
68352 / 3 = 22784.0

 

[Basic]

Why settle for "divide by 3" when you can go for "divide by 9"?

 

[Beafy]

Quite a clever idea actually...
If you know that you can test for divisibility (is that even a word?) by 3 by adding the digits and divide the resulting number by 3, the basis of why your approach works becomes a little bit clearer, IMO.

 

[Sage]

Quite a clever idea actually...
If you know that you can test for divisibility (is that even a word?) by 3 by adding the digits and divide the resulting number by 3, the basis of why your approach works becomes a little bit clearer, IMO.

wait... so this test for divisibility by 3 is a known approach? I thought I had discovered something all on my own

 

[OpenGL guy]

It makes even more sense if you do your math in modulo. Because 10 = 1 mod 3, 12345 = 1 + 2 + 3 + 4 + 5 mod 3 = 15 mod 3 = 1 + 5 mod 3 = 6 mod 3 = 0. Similarly for mod 9.

11 is also not bad since 10 = -1 mod 11, so you get 1 or -1 depending on which power of 10.