Abstract: An educational and recreational mathematical device comprises a ring or set of concentric rings or a band made endless or adapted to have ends thereof fastened to make them endless and a plurality of individual digits imprinted on the band or each ring at regularly spaced intervals. The digits when all read consecutively as a number constitute a quotient obtained by dividing a number constituted of (p-1)/n nines, in which P is a prime number greater than 5 and n is an integer at least 1, by P and adding to the left-hand end of said quotient any number of zeros necessary to increase the number of digits in the quotient to (p-1)/n or a specially chosen multiple of the quotient thus derived, n being so selected that (p-1)/n nines is the minimum number of nines divisible by P so that the quotient is an integral number.

Abstract: An educational and recreational mathematical kit comprises a set of n square sticks and a plurality of individual digits imprinted on each of the four sides of each of the sticks. The digits on one side of one of the sticks constitute a number which is a quotient obtained by dividing a number constituted of (P-1)/n nines, in which P is a prime number greater than 11 and n is an integer at least 2, by P, n being so selected that (P-1)/n nines is the minimum number of nines divisible by P so that the quotient is an integral number.