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#1 2012-10-29 19:51:18
- Harold
- Guest
Multifactorial
How do you define multifactorial?I know what it is,but how do you define it?I know how to define factorial.
#2 2012-10-29 20:12:14
- anonimnystefy
- Real Member
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Re: Multifactorial
It can be defined recursively:http://en.wikipedia.org/wiki/Factorial#Multifactorials
The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“A secret's worth depends on the people from whom it must be kept.” ― Carlos Ruiz Zafón
#4 2012-10-29 23:26:57
- bobbym
- Administrator
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Re: Multifactorial
Hi Harold;
Did you try one? Say for k = 3.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#5 2012-10-29 23:48:16
- Harold
- Guest
Re: Multifactorial
Well,if I try n=11,k=3,then11!!!=11*8*5*2(as 11 mod 3=2) =880,is it correct?
#6 2012-10-30 00:09:14
- bobbym
- Administrator
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Re: Multifactorial
Hi;
That is correct. Now what do you get for 20!!!! ?
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#7 2012-10-30 00:47:18
- Harold
- Guest
Re: Multifactorial
Well,thank you,I love solving problems,now,20!!!!,so n=20 and k=4
20!!!!=20(20-4)(20-4*2)(20-4*3)...(4) [as 20 mod 4=0]=20*16*12*8*4=122880.
#8 2012-10-30 00:57:27
- bobbym
- Administrator
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Re: Multifactorial
Hi;
That is correct. Your formula looks fine to me. Although there is a better one on that page that anonimnystefy sent you.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.
#9 2012-10-30 01:40:30
- Harold
- Guest
Re: Multifactorial
But,I am confused,if I do 11!!! by the method in wikipedia,I get 11!!!=11(8!!!)=11(8(5!!!))=11(8(5(2!!!)))=11(8(5(1))) [as 0<2<3] =440
and by my method,I get 11!!!=11(11-3)(11-2*3)...(2)=11*8*5*2=880
which is correct ??
#10 2012-10-30 01:44:34
- bobbym
- Administrator
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Re: Multifactorial
2!!! = 2 not 1.
In mathematics, you don't understand things. You just get used to them.
Probability is the most important concept in modern science, especially as nobody has the slightest notion what it means.
90% of mathematicians do not understand 90% of currently published mathematics.