Question 335891
if you are looking for "different orderings" its not combinations but permutations that you need to focus on.
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Number of different orderings of NNNNBBBBBB  (where N=novel, B=biographies)
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since there are a total of 8 novels 
the number orderings for the novels is 8*7*6*5 basically you first have 8 novels to choose from, then 7 novels after the first novel is chosen and so on.
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since there are a total of 10 biographies 
the number orderings for the biographies is 10*9*8*7*6*5 basically you first have 10 biographies to choose from, then 9 biographies after the first biography is chosen and so on.
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Answer:   (8*7*6*5)*(10*9*8*7*6*5)=254,016,000
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NOte this can be represented as (8P4)*(10P6) in permutation notation