Is 8 Your Lucky Number and What Does It Mean?

[Greg Bernhardt]

What is your favorite number and why? Is it lucky? Mathematically or aesthetically beautiful? Symbolic?

 

[jackwhirl]

Zero. It's just so dang useful.

 

[S.G. Janssens]

I would say $e$. Sorry, this choice is not very original, but its profound connection with differential equations and time evolution in general does it for me.

 

[QuantumQuest]

Number 8. I think that is aesthetically beautiful, can be turned upside - down and still recognize it and turn it 90 degrees to the left or right and lo and behold: infinity!

 

[jtbell]

42, of course!

 

[fresh_42]

$2$. I've always been fascinated by $2+2=2\cdot2=2^2$. In addition it is the first "real" number, Peano's start off if you like, the first example of a characteristic $\neq 0$, the reason why we can discuss this here, and last but not least: I like my Fermions.

Edit: And of course 4-O-9.

 

[jim mcnamara]

δ = 4.669201 ... Feigenbaum's constant. Got me interested in fractals in the late 1980's. Wrote lots of code, wasted lots of paper and printer toner. Had a ton of fun. Side effect: Had to learn postscript language run an Apple graphics printer. Which I still use sometimes. Piddling around can sometimes create the need to learn new things.

@QuantumQuest Isn't the analemma a kind of "sideways" eight as well?

 

[QuantumQuest]

@QuantumQuest Isn't the analemma a kind of "sideways" eight as well?

Yes, but it is a diagram with the form of a slender figure-eight.

 

[SW VandeCarr]

711! It must be really lucky.

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Calculator Use
Instead of calculating a factorial one digit at a time, use this calculator to calculate the factorial n! of a number n. Enter an integer, up to 4 digits long. You will get the long integer answer and also the scientific notation for large factorials. You may want to copy the long integer answer result and paste it into another document to view it.

What is a Factorial?
A factorial is a function that multiplies a number by every number below it. For example 5!= 5*4*3*2*1=120. The function is used, among other things, to find the number of way “n” objects can be arranged.

Factorial
There are n! ways of arranging n distinct objects into an ordered sequence.
n
the set or population
In mathematics, there are n! ways to arrange n objects in sequence. "The factorial n! gives the number of ways in which n objects can be permuted."[1] For example:

• 2 factorial is 2! = 2 x 1 = 2
  -- There are 2 different ways to arrange the numbers 1 through 2. {1,2,} and {2,1}.
• 4 factorial is 4! = 4 x 3 x 2 x 1 = 24
  -- There are 24 different ways to arrange the numbers 1 through 4. {1,2,3,4}, {2,1,3,4}, {2,3,1,4}, {2,3,4,1}, {1,3,2,4}, etc.
• 5 factorial is 5! = 5 x 4 x 3 x 2 x 1 = 120
• 0 factorial is a definition: 0! = 1. There is exactly 1 way to arrange 0 objects.

Factorial Problem 1
How many different ways can the letters in the word “document” be arranged?

For this problem we simply take the number of letters in the word and find the factorial of that number. This works because

 

[kith]

Although probably not what the OP had in mind, I really like the imaginary unit i for its mathematical beauty.

Starting with the natural numbers, people have struggled with the expansion of the number system for centuries. Successive expansions can be put in a very elegant scheme, namely the introduction of new solutions to polynomial equations which didn't have solutions previously. For example the equation x + 1 = 0 doesn't have a solution using only natural numbers, but it has a solution if we introduce negative numbers.

Naturally, we may be interested in the question whether the process of inventing new numbers (negative numbers, fractions, irrationals, ...) comes to an end and it turns out it does. If we already have the real numbers, we mainly need to invent solutions for one additional type of polynomial equation: those where the square of x is a negative number. The easiest equation of this type is x^2 + 1 = 0 and its solution is called the imaginary unit i. So i kind of marks the end point of a long mathematical journey. (In technical terms, the complex numbers are said to be "algebraically closed".)

Viewed from a different angle, i allows us to treat the elements of the vector space \mathbb{R}^2 as numbers (more precisely we get the field of the complex numbers). This is really cool and remarkable and the additional structure leads to many powerful and beautiful theorems in complex analysis.

 

[Mark44]

Edit: And of course 4-O-9.

OK, I'll bite. What's the significance of this number to you?
It makes me think of the Beach Boys song, "409 " -- http://www.bing.com/videos/search?q...t=she's+real+fine+my+409+beach+boys&FORM=VDRE

 

[fresh_42]

OK, I'll bite. What's the significance of this number to you?
It makes me think of the Beach Boys song, "409 " -- http://www.bing.com/videos/search?q=she's+real+fine+my+409+beach+boys&qpvt=she's+real+fine+my+409+beach+boys&FORM=VDRE

You know I'm simple minded enough to like their music.

 

[PeroK]

The number 39 has recurred in my life. When I was growing up, my mum's house was number 39 and my grandmother's house was also 39 When I started work, my first place in Nottingham was number 39, and now in London I have the luxury of a shed out back for my bike, which is number 39.

 

[HRubss]

25, I love middle numbers (or numbers that end in 5) and it just so happened to be my jersey number when I was playing HS football.

 

[fresh_42]

Here's another favorite number of mine:
$$ \omega = \inf_{ n \rightarrow \infty } \{ k \in \mathbb{R} \,\vert \, \text{ multiplications in }\mathbb{M}_n(\mathbb{R})\text{ can be done with } O(n^k) \text{ scalar multiplications } \}$$

 

[NascentOxygen]

711! It must be really lucky.

Not sure about bringing good luck, but there's definitely convenience!

 

[Ryan_m_b]

I've always liked 64. It's just aesthetically nice to me, not to big or small and can be repeatedly halved to make integers all the way back to 1. There's nothing rational about that I admit lol. 72 feels nice too, again not a very large or small number but can be easily divided by 2, 3, 4, 6, 8, 9, 12, 18, 24 and 36.

 

[SW VandeCarr]

Not sure about bringing good luck, but there's definitely convenience!

711 implies convenience like the store. 711! is my lucky number but it is convenient to calculate it online nowadays. Poor Isaac Newton would have had to do it by hand. However, I've read that he enjoyed doing long tedious calculations.

 

[mister mishka]

2, I honestly do not know why, but I've always liked that number ^^

 

[Fervent Freyja]

1. Simply because using it as the unit to count and measure has saved me time on a practical daily level. Without it, many simple things would take much longer and some things wouldn't be possible to do at all without a system to handle multiple things. What do other numbers mean without it? It is the backbone of modern civilization, really. A glorious number!

 

[Algr]

. So i kind of marks the end point of a long mathematical journey. (In technical terms, the complex numbers are said to be "algebraically closed".)

Viewed from a different angle, i allows us to treat the elements of the vector space \mathbb{R}^2 as numbers (more precisely we get the field of the complex numbers). This is really cool and remarkable and the additional structure leads to many powerful and beautiful theorems in complex analysis.

So there are no unsolvable equations in the complex numbers? I don't think so. In fact I've brought up one previously:

Y<1
Y+X<=1
Solve for X (That works for all reals.)

The last time I brought this up people were using dodges that sounded a lot more like politics then math. (Hence the reals stipulation above. )

As for my favorite number. Well, zero is my hero. :) And there appears to me more then one kind of zero in the reals.

 

[Bystander]

Zero. It's just so dang useful.

Well, zero is my hero. :)

Mort Walker fans? "Me?" 555, "The Triple Nickel."

 

[kith]

So there are no unsolvable equations in the complex numbers?

No polynomial equations, yes. The precise statement is given by the fundamental theorem of algebra.

Y<1
Y+X<=1

That's not an equation but a set of inequalities.

 

[Evo]

Two.

 

[Algr]

That's not an equation but a set of inequalities

But it is the clearest way to describe the issue, and I'm sure you can see the intent.

 

[kith]

But it is the clearest way to describe the issue, and I'm sure you can see the intent.

No, I can't see what concerns you. The fundamental theorem of algebra tells us that every polynomial equation has a solution in the complex numbers. If we drop the constraint that our equation needs to be a polynomial equation, it is easy to construct examples which don't have a solution in the complex numbers. For example, \sin(|z|) = 2.

I don't see an issue here and I don't understand why you bring up inequalities in response to these statements about equations.

Also this is getting off topic. If you want to discuss it further, you should open a new thread or ask the mentors to fork our discussion from this thread.

 

[Rubidium_71]

71

 

[Ssnow]

$4$

 

[Tsu]

73

 

[Choppy]

$J = (7^{e - 1/e} - 9) \cdot \pi^{2}$

 

[epenguin]

1729 before anyone else claims it!

This is the number (least one that is sum of two cubes writeable in more than one way) in the famous Hardy anecdote about Ramanujan.

I did actually see about 10 years ago a London taxi with registration plate TXI1729.

I bet not a lot of people here have done that. So lifetime acheivement!

 

[tionis]

拾叁

 

[Svein]

17. There is an old mathematics adage: If you can prove it for x = 17, then it has a good chance to be true for all x.

 

[EnumaElish]

Pi. It's probably the most or the second most famous irrational number. And it distinctly smells of baked apples and cinnamon.

 

[Carrock]

7.
The smallest of the more 'interesting' primes.
e.g. when I was learning how to express x/y as a decimal, it was 1/7, 2/7, 3/7 etc that made me realize decimals weren't just an uninteresting variation on fractions.
i.e. 0.142857... , 0.285714... , 0.428571... etc

 

[SW VandeCarr]

Both 0 and 1 are mentioned as favorite numbers here. It's apparently assumed that by "number" we mostly mean the natural numbers or the non-negative integers. The latter includes 0. However 0 and 1 are neither prime numbers nor composite numbers. They are specifically excluded in the Fundamental Theorem of Arithmetic. Zero and one are algebraic identities. Zero is the additive identity and one is the multiplicative identity. The latter is the reason why 1 can't be prime. It is a "factor" of every natural number. To properly define "prime number" we must exclude 1.

It seems even mathematicians don't know exactly what to do with 0 and 1 in terms of classification. It all seems a bit awkward.

 

[bigfooted]

33550336, It was the result of one of my first computer programs!
It convinced me that a connection must exist between perfect numbers and Mersenne primes. You can read all about it on wikipedia now, but it was more difficult to find such information in a small farming village in 1994.

 

[Kevin McHugh]

I like pi
And e is cool
Favorite is i

 

[Wastrophysicist]

My favourite number... What a curious question.
It is "-1". Why such a -1 be interesting.?
Well, we could set -1 as a very beautiful combination of number e, number i and number phi.
Then, e^(i*π) = -1 !

 

[DiracPool]

8. Oh, I guess you eight one two

 

[DiracPool]

Then, e(i*π) = -1 !

I don't why people like this expression so much, because it has the minus sign in it? I think the most poetic form of Euler's identity is "e^i2π=1" This is a very clean expression, no fussy minus signs, and brings it all around full circle

 

[Wastrophysicist]

I don't why people like this expression so much, because it has the minus sign in it? I think the most poetic form of Euler's identity is "e^i2π=1" This is a very clean expression, no fussy minus signs, and brings it all around full circle

Indeed, my e^(i*π) = -1 is not the better. Maybe it will be e^(i*π) + 1 = 0 since it has number e, i , π, 1 and 0. I wrote e^(i*π) = -1 because it simplifies the expression and gives a "-1" which is a number that is not as much as popular as 0. I just wanted to remark that -1 could be a weird and beautiful expresion. I don't know if "e^i2π=1" will be as much as beautiful, since there is a "2" in it, and it is not as important nor beautiful as e, i , π, 1 or 0 (despite that 2 has its own rare properties, like to be the only prime number that is even).

 

[DiracPool]

I don't know if "e^i2π=1" will be as much as beautiful, since there is a "2" in it, and it is not as important nor beautiful as e, i , π, 1 or 0

I love your passion here, but I still think that my expression is the most beautiful. The fact is that we are stuck with PI and I don't see that changing in the foreseeable future. But a more elegant form of the Euler identity would be to use the Tau term which would eliminate the "2" that you seem to have a problem with. So, it would be e^iτ=1.

 

[Kevin McHugh]

8. Oh, I guess you eight one two

ROTFLMAO Well done DP.