Mathematicians isolate graphs with extreme traits under simple names that stick for generations. The Balaban 10-cage realizes the (3,10)-cage with 70 vertices. Errera and Kittell graphs relate to the four color theorem. The Frucht graph is the smallest 3-regular with trivial automorphism group. Circuit designers draw on the Goldner-Harary and Wagner graphs for planar embeddings in printed circuit board layouts.

Math and paper size A4 is half the size of A3, one-fourth of A2, and one-sixteenth of A0. The A0 sheet has an area of exactly 1 square meter (though it isn’t a square). All A-series paper sizes share the same aspect ratio, where the ratio of length to width is √2. This unique property allows each size to be scaled up or down without changing its proportions or causing distortion.