In mathematics. Forty is a composite number, an octagonal number, and as the sum of the first four pentagonal numbers 1+5+12+22=40, it is a pentagonal pyramidal number. Adding up some subsets of its divisors (e.g., 1, 4, 5, 10 and 20) gives 40, hence 40 is a semiperfect number.; Given 40, the Mertens function returns 0. 40 is the smallest number n with exactly 9 solutions to the equation φ(x ...A wiki (/ ˈ w ɪ k i / WIKee) is a hypertext publication collaboratively edited and managed by its own audience directly using a web browser.A typical wiki contains multiple pages for the subjects or scope of the project and could be either open to the public or limited to use within an organization for maintaining its internal knowledge base.. Wikis are enabled by wiki software, otherwise ...
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