Strobogrammatic number Strobogrammatic number A strobogrammatic number is a number whose numeral is rotationally symmetric, so that it appears the same when rotated 180 degrees. In other words, the numeral looks the same right-side up and upside down (e.g., 69, 96, 1001). A strobogrammatic prime is a strobogrammatic number that is also a prime number, i.e., a number that is only divisible by one and itself (e.g., 11). It is a type of ambigram, words and numbers that retain their meaning when viewed from a different perspective, such as palindromes. When written using standard characters (ASCII), the numbers, 0, 1, 8 are
Diple (textual symbol) Diple (textual symbol) Diple (, meaning double, referring to the two lines in the mark >) was used in margins to draw attention to something in text. It is sometimes also called antilambda because the sign resembles a Greek capital letter lambda (Λ) turned upon its side. In some ways its usage was similar to modern day quotation marks; guillemets (« »), used for quotations in French, are derived from it. Isidore remarks in his "Etymologiae" (I.XXI.13) that the diple was used to mark quotations from the Bible. He also talks about "diple peri strichon" (or "sticon"), which was used