This article gives two methods of resolving natural numbers into prime factors. Depending upon the number that is being resolved, one method may be better to use than the other. However, it is difficult to tell beforehand which is the better method to employ. Examples are given. (Author/MA)

Tests for divisibility in bases 2 through 10 are presented. Two strategies used by a group of fourth-year students are described. (MNS)

The focus of these worksheets is on whole-number numeration using resource materials such as newspapers, tables of contents, indexes, and almanacs. Notes for the teacher are included. (MNS)

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)

The author cites research from students' misconceptions of decimal notation that indicates that many students treat decimals as another whole number to the right of the decimal point. This "whole number thinking" leads some students to believe, in the context of comparing decimals, that "longer is larger" (for example, 0.45 is…

Mathematics activities and materials for teaching and reinforcing number concepts are presented. The activities, which rely primarily on number cards, are divided into the following sections: (1) sets less than ten; (2) the teen numbers; (3) sets and numerals to 100; (4) numeration; and (5) words that represent numbers (e.g., "one=1").…

An ancient Chinese method of calculating ages indirectly can provide interesting practice with number concepts. (SD)

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)