# De utilitate mathematicae 21

Theon Smyrnaeus, De utilitate mathematicae, Paragraph 21. Ancient Greek.

Canonical: https://interlinea.aeterna-institute.org/library/greek/theon-smyrnaeus/de-utilitate-mathematicae/21

ἔτι τῶν συνθέτων ἀριθμῶν οἱ μὲν ἰσάκις ἴσοι εἰσὶ καὶ τετράγωνοι καὶ ἐπίπεδοι, ἐπειδὰν ἴσος ἐπὶ ἴσον πολλαπλασιασθεὶς γεννήσῃ τινὰ ἀριθμόν, [ὁ γεννηθεὶς ἰσάκις τε ἴσος καὶ τετράγωνός ἐστιν] ὡς ὁ δ΄, ἔστι γὰρ δὶς β΄, καὶ ὁ θ΄, ἔστι γὰρ τρὶς γ΄· οἱ δὲ ἀνισάκις ἄνι- σοι, ἐπειδὰν ἄνισοι ἀριθμιοὶ ἐπʼ ἀλλήλους πολλαπλα- σιασθῶσιν, ὡς ὁ ϛ΄· ἔστι γὰρ δὶς γ΄ ϛ΄.

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Theon Smyrnaeus, De utilitate mathematicae, ed. Eduardus Hiller. Text: The Greek Library, from the Perseus Digital Library and other open sources, CC BY-SA 4.0. Changes: apostrophes normalised and the text divided into reading sections by Interlinea.
License: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/). Source: https://thegreeklibrary.pages.lisn.upsaclay.fr/works/tlg1724.tlg001.local001/.