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# looking for a math formula

Topic closed. 8 replies. Last post 11 years ago by RJOh.

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New Member
Montreal
Member #55662
October 13, 2007
3 Posts
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 Posted: October 13, 2007, 8:40 pm - IP Logged

Do someone know the formula to calculate how many X combination in Y !

For example lets say i wanna know how many 20 numbers combination bettween 1 and 70 !

United States
Member #13130
March 30, 2005
2171 Posts
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 Posted: October 13, 2007, 9:21 pm - IP Logged

To calculate the number of combinations of n elements taken r at a time.

n C r = n! / [(n-r)! * r!]

70 C 20 = 70! / [(70-20)! * 20!]

= 70! / [50! * 20!]

= 1.6188 e 17

mid-Ohio
United States
Member #9
March 24, 2001
20210 Posts
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 Posted: October 13, 2007, 9:25 pm - IP Logged

C(20,70) = 1.618846036626579D+17  It's approximately 161,884,603,662,658,000.  You use the same formula that you use to calculate the number of smaller combinations within a pool of numbers but you will get the scientific notation when using your computer if the program can't handle more than 16 digits.

You might get more accuracy if you used a program designed to calculate keno odds or a scientific calculator.

* you don't need to buy more tickets, just buy winning ones *

New Member
Montreal
Member #55662
October 13, 2007
3 Posts
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 Posted: October 13, 2007, 9:43 pm - IP Logged

Wow ! Thank for the fast response guy's

NY
United States
Member #23835
October 16, 2005
3795 Posts
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 Posted: October 13, 2007, 9:56 pm - IP Logged

Even easier:

http://www.wiley.com/college/mat/gilbert139343/java/java05_applet.html

United States
Member #13130
March 30, 2005
2171 Posts
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 Posted: October 14, 2007, 12:31 am - IP Logged

nice little app, but it seems to not like numbers this big.

closest you can get are 70C18 and 80C16

CA
United States
Member #2987
December 10, 2003
832 Posts
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 Posted: October 14, 2007, 9:38 am - IP Logged

http://www.johnph77.com/math/kenocomp.html

No ads, nothing to sell, for informational purposes only.

gl

j

Blessed Saint Leibowitz, keep 'em dreamin' down there.....

Next week's convention for Psychics and Prognosticators has been cancelled due to unforeseen circumstances.

=^.^=

New Member
Montreal
Member #55662
October 13, 2007
3 Posts
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 Posted: October 14, 2007, 10:41 pm - IP Logged

http://www.johnph77.com/math/kenocomp.html

No ads, nothing to sell, for informational purposes only.

gl

j

All the info i was looking for is there !

mid-Ohio
United States
Member #9
March 24, 2001
20210 Posts
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 Posted: October 15, 2007, 4:40 pm - IP Logged

I stand corrected, when you use the scientific version of the calculator that comes in Windows to calculate 70!/(50! * 20!) the answer is not in scientific notation 1.618846036626579D+17 but in whole numbers 161884603662657876.

* you don't need to buy more tickets, just buy winning ones *

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