Question 541540
Assuming the order does not matter, you want the number of combinations of 9 things taken 5 at a time.
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The combinations may be denoted as:  C(9,5), <sub>9</sub>C<sub>5</sub> and in several other ways.
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{{{ C(9,5) = 9!/(5!*(9-5)!) = (9*8*7*6*5!)/(5! * 4!) }}}
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The 5! terms cancel
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{{{ (9*8*7*6)/(4*3*2) = 9*7*2 }}}
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The above change is because 4*2 cancels the 8 in the numerator and 6/3 = 2
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{{{ 9*7*2 = 126 }}}
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Done.