Question 631390
If you have a set of n different items (10 in this case), and you want to know how many ways you can choose k of them (2 in this case), the equation is:
{{{P=n!/(n-k)!}}}
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{{{P=10!/8!}}}
{{{P=10*9}}}
{{{highlight(P=90)}}}
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Good Luck,
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