Lagrange's theorem, in group theory, a part of mathematics, states that for any finite group G, the order of every subgroup of G divides the order of G. What are some of the applications of this...

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Extracted text: Lagrange's theorem, in group theory, a part of mathematics, states that for any finite group G, the order of every subgroup of G divides the order of G. What are some of the applications of this theorem in other fields?