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posted by 000 on Sunday, July 7, 2013 at 9:44pm.
How many ways can the number 30 be written as an ordered sum of 2s and 5s?
15 2's = one way 10 2's + 2 5's = 12!/(10!2!) ways 5 2's + 4 5's = 9!/(5!4!) ways 6 5's = one way Total=194
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