← euclid / The Thirteen Books of Euclid’s Elements Volume II / Book IX / Propositions / IX.26 ← Prev Next → [Folio 0421 | p. 415] PROPOSITION 26.¶ If from an odd number an odd number be subtracted, the remainder will be even. For from the odd number AB let the odd number BC be subtracted ; I say that the remainder CA is even. A C D B For, since AB is odd, let the unit BD be subtracted ; [VII. Def. 7]therefore the remainder AD is even. [VII. Def. 7]For the same reason CD is also even ; [IX. 24]so that the remainder CA is also even. Q. E. D. Dependency Graph¶ digraph { bgcolor="transparent"; node [shape=box, style="rounded,filled", fontname="Helvetica", fontsize=11, color="#d6d3cd", fontcolor="#ffffff"]; edge [color="#8c857b", fontcolor="#8c857b", arrowsize=0.75]; rankdir="TB"; "VII.def.1" [label="VII.def.1", fillcolor="#224422", tooltip="VII.def.1: An unit is that by virtue of which each of the things that exist is called one.", URL="../../../book_vii/definitions/index.html#vii-def-1", target="_top"]; "VII.def.6" [label="VII.def.6", fillcolor="#224422", tooltip="VII.def.6: An even number is that which is divisible into two equal parts.", URL="../../../book_vii/definitions/index.html#vii-def-6", target="_top"]; "VII.def.7" [label="VII.def.7", fillcolor="#224422", tooltip="VII.def.7: An odd number is that which is not divisible into two equal parts, or that which differs by an unit from an even number.", URL="../../../book_vii/definitions/index.html#vii-def-7", target="_top"]; "IX.24" [label="IX.24", fillcolor="#222244", tooltip="IX.24: If from an even number an even number be subtracted, the remainder will be even.", URL="../24/index.html", target="_top"]; "IX.26" [label="IX.26", penwidth=2.5, color="#e8b85a", fillcolor="#4a453b", tooltip="IX.26: If from an odd number an odd number be subtracted, the remainder will be even.", URL="index.html", target="_top"]; "VII.def.7" -> "VII.def.1"; "VII.def.7" -> "VII.def.6"; "IX.24" -> "VII.def.6"; "IX.26" -> "VII.def.6"; "IX.26" -> "VII.def.7"; "IX.26" -> "IX.24"; }