      # Factorial (n!)

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### #1 fvogado

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Posted 17 July 2019 - 05:51 PM

Hello I am newbie with Casio Calculators so I need a little help I am a happy owner of FX-9860gii

I want to solve this equation:

M!

X= ---------------

N!  x  (M-N)!

I know that can be solved using the Combination function (nCr ) but this is not the idea, the idea is to use X,M and N as variables.

When I try to "write" the equation I receive this answer "syntax error" but I do not know what kind of mistake I did. I wrote the equation in the same way that I wrote here.

If I write this equation, I do not receive the syntax error message so I think the problem is the factorial symbol (!)

M

X= ---------------

N  x  (M-N)

### #2 CalcLoverHK

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Posted 18 July 2019 - 04:56 AM

M!

X= -----------------   seems have infinite solutions at all.

N!(M-N)!

### #3 fvogado

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Posted 18 July 2019 - 05:07 AM

Hello, Is not working for me...

M!

X= -----------------   seems have infinite solutions at all.

N!(M-N)!

### #4 CalcLoverHK

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Posted 18 July 2019 - 05:10 AM

I tried this equation in NumWorks simulator, but it showed "The system is not linear". (Your equation is not linear I think?)

### #5 fvogado

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Posted 18 July 2019 - 05:16 AM

Is the formula of the Combinations, nothing special at all. The calculator can solve it.

I tried this equation in NumWorks simulator, but it showed "The system is not linear". (Your equation is not linear I think?)

Is the formula of the Combinations, nothing special at all. The calculator can solve it.

I tried this equation in NumWorks simulator, but it showed "The system is not linear". (Your equation is not linear I think?)

### #6 CalcLoverHK

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Posted 18 July 2019 - 05:24 AM

Maybe you can try X=M!÷(N!(M-N)!)?

### #7 fvogado

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Posted 18 July 2019 - 05:29 AM

not working Maybe you can try X=M!÷(N!(M-N)!)?

### #8 CalcLoverHK

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Posted 18 July 2019 - 05:34 AM

Well, what variable do you want to solve?

Since this formula has infinite solutions, you have to assume the value of the variables or type the possible value range of the variable you want to solve.

### #9 fvogado

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Posted 18 July 2019 - 05:41 AM

The idea is to get X,M or N if I give to the calculator 2 of them. Try the same formula without (!) and you will get the idea...

Well, what variable do you want to solve?

Since this formula has infinite solutions, you have to assume the value of the variables or type the possible value range of the variable you want to solve.

### #10 fvogado

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Posted 29 July 2019 - 03:22 PM

Hello, nobody has any idea how to solve it?

best regards

### #11 fvogado

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Posted 27 January 2020 - 04:32 PM

Hello, nobody has any clue how to solve it?

best regards

### #12 CalcLoverHK

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Posted 27 January 2020 - 11:22 PM

Sorry for late reply. It should be the problem of inputting "!".

The method of putting ! should be -> -> (should be PROB) ->

Solution reference: (Thanks to Planete-Casio member Hackcell) Hope this helps.

Cheers
CalcLoverHK

Edited by CalcLoverHK, 28 January 2020 - 09:21 AM.

### #13 DramIt

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Posted 30 January 2020 - 09:48 PM

Factorial (n!) works with number greater than zero and less than seventy.  Maybe open ended variables aren't allowed in the example shared.

### #14 siealex

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Posted 17 February 2020 - 06:37 PM

Try it on a TI-86, it supports factorials for real arguments (n!=Γ(n+1) ), not only for integer numbers, also it supports numbers up to 1e1000. Casio does not support probability functions (and other non-continuous functions) in equations, maybe the only way is programming. Or using approximations for factorials (like the Stirling's formula).

Edited by siealex, 17 February 2020 - 07:14 PM.

### #15 Tritonio

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Posted 11 March 2020 - 08:30 PM

You could write a program that iterates over all 70*70=4900 possible combinations for integers assigned to M an N until it finds a solution.

### #16 fvogado

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Posted 01 April 2020 - 11:32 PM

Sorry for late reply. It should be the problem of inputting "!".

The method of putting ! should be -> -> (should be PROB) ->

Solution reference: (Thanks to Planete-Casio member Hackcell) Hope this helps.

Cheers
CalcLoverHK

Hello!!!!

Did you try it?

Is not working for me...

best regards

Try it on a TI-86, it supports factorials for real arguments (n!=Γ(n+1) ), not only for integer numbers, also it supports numbers up to 1e1000. Casio does not support probability functions (and other non-continuous functions) in equations, maybe the only way is programming. Or using approximations for factorials (like the Stirling's formula).

Hello siealex, the formula are not the same. I think you get the idea and works for the TI, but try the same formula (is in the beginning of this topic)

Best regards

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