From Carlos Rivera's Prime Puzzles and Problems collection. Carlos asks for the general divisibility rules for any prime number.

Ways of telling whether one number divides another without actually carrying the division through, constructed here in terms of the digits of the number.

Jim Loy explains the divisibility rules up to 11, including a detailed study of 7.

From the NRICH Maths Project Cambridge, England. Dr. Tim Rowland explains the smaller rules and looks at the rules to 7, 11, 13, and 19.

From the Furman University Electronic Journal of Undergraduate Mathematics. Apoorva Khare's paper is available as an abstract, DVI, and PostScript.

A card game to teach divisibility rules.

Proof of the elementary division rules, plus some lesser-known rules for larger divisors and other bases.

Introduction to unbiased non-divisor and using it in mathematical proofs.