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April 06, 2026, 12:03:00 am
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Author Topic: Hard counting questions  (Read 1279 times)  Share 

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Mahan

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Hard counting questions
« on: March 05, 2017, 11:36:00 pm »
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1.What is the minimum number of numbers we have to remove from the set {1,..,1375} such that if we multiply the any two remaining elements the product is not in the set.
2.with digits 1 and 2 how many 5 digits numbers can be formed such that every two numbers have at least two different digits. For example 11111 and 12211 have at least two different digits but 11111 and 11112 do not.
« Last Edit: March 05, 2017, 11:52:53 pm by Mahan »
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Mahan Ghobadi

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