Question

can anybody explain what is amstrong number ?

Answer 1

For example,
\[153=1^3+5^3+3^3\\
370=3^3+7^3+0^3\\
371=3^3+7^3+1^3\\
407=4^3+0^3+7^3.\]
(Copied form WIkipedia)

Answer 2

@kc_kennylau I like that you said you got it from Wikipedia the free encyclopedia.

Answer 3

ok thanks guys !

Answer 4

is there a formula to generate these

Answer 5

@Isaiah.Feynman copyright is very important :)

Answer 6

@beccaboo022a no in my knowledge

Answer 7

@Nascent no problem :)

Answer 8

i think so, we dont have a formula for generating pythagorean triples also i think
a^2 = b^2+c^2

Answer 9

pythagorean triples is theorem

Answer 10

@kc_kennylau I know some guy who always copied solutions and posed like he knew them

Answer 11

do u guys have any idea how to write an algorithm to check armstrong number ?

Answer 12

In which language?

Answer 13

Checking if an integer named \(i\) is an armstrong number:
Let \(n\) be the number of digits of \(i\).
Let \(\mbox{count}\) be an integer which is 0.
From \(k\)=1 to \(k\)=\(n\):
Add the nth power of the kth digit of \(n\) to \(\mbox{count}\).
If \(\mbox{count}\)=\(i\):
Say yes.
Otherwise:
Say no.

Answer 14

digits <= split(number)
sum_of_cubes <= 0
WHILE digits
digit <= chop(digits)
sum_of_cubes += digit
ENDWHILE

IF sum_of_cubes == number
Display Yes, its an armstrong number
ENDIF

Answer 15

thats the pseudo code for checking armstrong number.
if you have an algorithm for generating armstrong numbers let me know. im interested :)

Answer 16

@beccaboo022a basically you can check the numbers one by one lol

Answer 17

thanks @beccaboo022a @kc

Answer 18

@kc_kennylau

Answer 19

lol thats bruteforce

Answer 20

@beccaboo022a who said you can't use bruteforce? :P

Answer 21

@Nascent no problem :)

Answer 22

bruteforce is not fit to called an algorithm in my dictionary of definitions ;)

Answer 23

what do you mean, a pattern in armstrong #?

Answer 24

like, we dont have a pattern for generating prime numbers
why do mathematicians spend so much in trying for an algorithm to generate prime numbers ?

Answer 25

http://oeis.org/A005188
This is the list of some of the Armstrong numbers. Note that there is FINITELY many Armstrong number in a given base.

Answer 26

http://screencast.com/t/fpv3mxE1lX

Answer 27

https://en.wikipedia.org/wiki/Narcissistic_number#Narcissistic_numbers_in_various_bases

Answer 28

I didn't know it till now, and I find it absolutely amazing that the list is finite.

Answer 29

hummm things are really amazing !

Answer 30

I also am aware of the huge gap between 9474 and 54748.

Answer 31

@Nascent yes indeed :)

Answer 32

how can we display fibonacci's series ?

Answer 33

http://mathworld.wolfram.com/NarcissisticNumber.html
Complete list of Armstrong # :)

Answer 34

what do you mean by display?

Answer 35

i mean to write a program

Answer 36

Pseudocode:

Let \(a\) be an integer which is 1.
Let \(b\) be an integer which is 1.
Let \(c\) be an undefined integer.
Print \(a\).
Print \(b\).
Define \(c\) as \(a+b\).
Loop forever:
Print \(c\).
Define \(a\) as \(b\).
Define \(b\) as \(c\).
Define \(c\) as \(a+b\).

Answer 37

in C++

Answer 38

Java:

int a=1;
int b=1;
int c;
System.out.println(a);
System.out.println(b);
c=a+b;
while(true){
System.out.println(c);
a=b;
b=c;
c=a+b;
}

Answer 39

sorry I don't know C++, please convert it yourself

Answer 40

It's pseudocode's function to let any programmer understand what's going on

Answer 41

ok !

Answer 42

:)

Answer 43

i got it now !

Answer 44

thank you once again @kc_kennylau

Answer 45

no problem at all :)

Answer 46

@kc_kennylau can you explain more about that algorithm !

Answer 47

Fibonacci series is 1, 1, 2, 3, 5, 8, 13, ...

Each term is generated by adding the last two terms together, i.e.:
1+1=2
1+2=3
2+3=5
3+5=8
5+8=13

Answer 48

not this one

Answer 49

which

Answer 50

the another one one with armstrong

Answer 51

So, let's look at the number \(\color{green}{54748}\).

It has 5 digits. (n=\(\color{red}5\))
count=\(\color{green}5^{\color{red}5}+\color{green}4^{\color{red}5}+\color{green}7^{\color{red}5}+\color{green}4^{\color{red}5}+\color{green}8^{\color{red}5}\)

Then we check if count equals 54748.

Answer 52

got to go see you after an hour sorry :/

Answer 53

FYI, i=54748

Answer 54

ok !