Two unequal numbers (being) laid down, and the lesser being continually subtracted, in turn, from the greater, if the remainder never measures the (number) preceding it, until a unit remains, then the original numbers will be prime to one another. * For two [unequal] [numbers]bookofproofs$2315, $AB$ and $CD$, the lesser being continually subtracted, in turn, from the greater, let the remainder never measure the (number) preceding it, until a unit remains. * I say that $AB$ and $CD$ are prime to one another - that is to say, that a unit alone measures (both) $AB$ and $CD$.
See co-prime numbers.
Proofs: 1
Proofs: 1