Definition: 7.10: OddTimesOdd Number
And an oddtimesodd number is one (which is) measured by an odd number according to an odd number.
Modern Formulation
see product of two odd numbers.
Notes
 Actually, this definition is a proposition rather than a definition of Book 7.
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References
Adapted from (subject to copyright, with kind permission)
 Fitzpatrick, Richard: Euclid's "Elements of Geometry"
Adapted from CC BYSA 3.0 Sources:
 Prime.mover and others: "Pr∞fWiki", https://proofwiki.org/wiki/Main_Page, 2016