An activity providing practice with whole number addition and subtraction, as well as enlarging on the idea of numeration systems, is described. (DT)

This game of strategy for two players is an adaptation of mastermind to a pencil-and-paper game. Rules and examples are given. (MP)

Problems are discussed in which addition facts are presented using words instead of numbers. The letters are then replaced by numbers that will make the addition problems correct. (MP)

Number bases other than ten can be introduced effectively by presenting fictional civilizations which use them. (SD)

A concrete approach to prime numbers is presented using rectangles and triangles to construct a building for each number so that each story represents a pair of factors and the triangular-shaped roof represents the number. (MP)

Three worksheets explore perfect, deficient, abundant, and amicable numbers by attaching mystical connotations to numbers and their divisors. (JT)

This article discusses the use of the balance beam in developing concepts of equality and inequality and in showing the basic arithmetic operations. (DT)

The system of International Standard Book Numbers uses a check code based on modular arithmetic. This system, the use of a simple machine to compute check digits, and related classroom activities are described. (SD)

Activity questions based on the prime factorization of numbers can be answered by reference to the lattice structure of factors. (SD)

Activities involving set union and intersection, graphing solutions of open sentences, and negation are described. These activities afford students with opportunities for computational practice as well as instruction on equations and inequalities. (SD)

Rational points in the plane were defined as points having both coordinated rational. Students solved several problems linking rational points with lines, circles, and other geometric figures. (SD)

Activities are described which make use of rectangular arrays as a means of illustrating multiplication facts and the distributive property. (DT)

The rules for seven different games with playing cards are given. Educational uses are discussed briefly for each of the games. (DT)

The activities presented are all designed to encourage children to learn about the structure of whole numbers by looking at number patterns in various ways. (DT)

Instruction on properties of whole numbers, the meanings of operations on whole numbers, symbolic representation and algorithms for completing these operations is discussed. Many activities appropriate to each of these topics, and suitable for primary school children, are presented. (SD)