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) to draw attention to separate concepts and "diple periestigmene" used (like obelos) to mark dubious passages. "Diple obolismene" was used according to Isidore to separate sentences in comedies and tragedies, so its usage was similar to that of paragraphos. 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 («