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
Actual infinity actu non datur" as an irrefutable principle. (G. Cantor [3, p. 174]) The number of points in a segment one ell long is its true measure. (R. Grosseteste [9, p. 96]) Actual infinity exists in number, time and quantity. (J. Baconthorpe [9, p. 96]) During the Renaissance and by early modern times the voices in favor of actual infinity were rather rare. The continuum actually consists of infinitely many indivisibles (G. Galilei [9, p. 97]) I am so in favour of actual infinity. (G.W. Leibniz [9, p. 97]) The majority agreed with the well-known quote of Gauss: I protest against