Homeschool Math
Homeschool Math: Prime Factorization of Three Digit Numbers
This lesson shows examples of how to get started with the prime factorization of three-digit or larger numbers, using a factor tree. includes numerous practice exercises.
Calculator Soup
Calculator Soup: Prime Factorization Calculator
Use this prime numbers calculator to find all prime factors of a given integer number up to 1 trillion. This calculator presents prime factors of a number, prime decomposition in exponential form, CSV (comma separated values) list of...
ClassFlow
Class Flow: Working With Prime and Composite Numbers
[Free Registration/Login Required] This flipchart allows students to practice working with prime and composite numbers. Students learn how to do prime factorization.
Shodor Education Foundation
Shodor Interactivate: Factorize
This Shodor site gives a brief explanation of factorization, and it allows you "to find all of the factorizations of a given number and then draw the product as the area of a rectangle on a grid."
Cool Math
Coolmath: Pre Algebra: Prime Factorizations
In this tutorial, students learn how to do prime factorization by a few different methods, including factor trees and factor stacks. The exercises work their way up from 2-digit numbers up to 5 digits. Includes practice problems.
Cool Math
Coolmath: Pre Algebra Factorizations
Learn about "factorization" from Cool Math. Several examples and practice problems are provided.
National Council of Teachers of Mathematics
The Math Forum: Finding the Greatest Common Factor of Two Numbers
Math Forum response to question about finding the greatest common factor by using the factoring tree method.
University of Waterloo (Canada)
Wired Math: Primes and Prime Factors [Pdf]
Explore primes, prime factors, and composites using this collection of worksheets. Lots of detailed examples, interesting math facts, and colorful visuals. Acrobat Reader required.