I am thinking of a two digit number, AB, such that A x B=AB/2, and A+B=AB/4. What is the number AB?
"Pure mathematics is, in its way, the poetry of logical ideas."
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In mathematics, you don't understand things. You just get used to them.
Of course that result can be rigorously obtained, but who cares?
Combinatorics is Algebra and Algebra is Combinatorics.