Possibities of 1 to 45

heshika · Jun 25, 2009, 07:58 AM

Hi All,

I just have mathematics question as how many possibilities in following number range as

1 to 45.

It does not matter which order. Only thing same number set should not be repeated.There are few conditions as 7 numbers should be in the line and does not matter any order is it.only thing same number should not be repeat.

Eg :- 5, 8, 15 , 18 ,20, 40,45

6,7,15,20,21,23,43

However I jut want to know these possibilities for those 45 numbers.

Unknown008 · Jun 25, 2009, 08:11 AM

You have to use combinations here, since you don not want repetitions. There are 45 numbers, out of which, 7 are to be taken. So,

$^{45}C_7=45379620$

jcaron2 · Jun 25, 2009, 10:27 AM

And in case you aren't familiar with combinations, the formula is:

$_nC_r\;=\;\frac{n!}{r!\,(n-r)!}\\<br /> _{45}C_7\;=\;\frac{45!}{7!\,\cd\,38!}\;=\;\frac{45 \cd 44 \cd 43 \cd 42 \cd 41 \cd 40 \cd 39}{7 \cd 6 \cd 5 \cd 4 \cd 3 \cd 2 \cd 1}\;=\;45379620<br /> <br />$

heshika · Jun 26, 2009, 02:34 AM

Originally Posted by Unknown008

You have to use combinations here, since you don not want repetitions. There are 45 numbers, out of which, 7 are to be taken. So,

$^{45}C_7=45379620$

thanks.I will try to figure out this.:)

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