Abstract.  Consciously or unconsciously, part of the apparatus that architects use in their daily fabrications of the built environment grows out of their understanding of numbers and numerals. Marco Frascari examines the use of number and especially the number 11 in the architecture of Carlo Scarpa. In Scarpa’s opus, it is true that One and One Equals Two, but it is also wonderfully true that A Pair of Ones Makes an Eleven.