McGraw Hill
Glencoe: Self Check Quizzes 1 Prime Factors
Use Glencoe's randomly generated self-checking quiz to test your knowledge of prime factors. Each question has a "Hint" link to help. Choose the correct answer for each problem. At the bottom of the page click the "Check It" button and...
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.
Mangahigh
Mangahigh: Number: Find Prime Factors
Test your knowledge of prime factors of two-digit numbers.
Mathigon
Mathigon: Math Foundations: Divisibility and Primes: Factors and Multiples
This lesson focuses on factors and multiples; it explains each and provides practice activities and a quiz.
CK-12 Foundation
Ck 12: Arithmetic: A Number as a Product of Its Prime Factors
[Free Registration/Login may be required to access all resource tools.] Write the prime factorization of given numbers.
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.
Math Is Fun
Math Is Fun: All Factors of a Number
Great tool that will find all factors of a number, not just the prime factors.
Varsity Tutors
Varsity Tutors: Hotmath: Practice Problems: Greatest Common Factor 2
Twenty-four problems present a variety of problems working with finding the greatest common factor and finding prime factorizations. They are given with each step to the solution cleverly revealed one at a time. You can work each step of...
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."
Discovery Education
Discovery Education: Web Math: Factor an Integer
WebMath gives a calculator to give all the factors of a number. Drop down menu can select just prime factors of number entered. Also discusses the definition of a factor.
Wolfram Research
Wolfram Mathworld: Prime Factorization
This site gives a wonderful explanation of prime factorization including a very helpful table in understanding prime decomposition. Look further down the page to get information on Gaussian primes.
Wyzant
Wyzant: Prime Factors Calculator
Students input a number to be factored and the WyzAnt calculator does the rest. Limitations include the fact that numbers which are negative or which contain primes bigger than 541 cannot be handled.
Amby Duncan-Carr
Prime Factorization: Amby's Resources
What is prime factorization? This site goes through a step-by step process explaining different ways to find the prime factorization.
Homeschool Math
Homeschool Math: Prime Factorization
This site contains a free lesson on Prime Factorization in which students learn by doing practice problems.
Math.com
Math.com: Greatest Common Factor/practice Calculator
A page which generates number pairs and allows the user to find and enter the GCF. Keeps a running tally of correct/incorrect answers and has links to in depth review, if needed.
Math Is Fun
Math Is Fun: Prime Factorization
Find a definition or prime numbers and prime factorization, as well as examples on how to find the prime factors of 12 and 147. Also, follow a link to a Prime Factorization Tool.
PBS
Pbs Learning Media: Patterns of Factors
Demonstrate your grasp of patterns and factors by sorting the numbers into the correct columns. This interactive table focuses on factor pairs and prime factors for the numbers 2 to 36.
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...
Mathigon
Mathigon: Math Foundations: Divisibility and Prime: Greatest Common Factors
This lesson focuses on the greatest common factors it poses real situations and asks students answer them and then it provides more information and more exercises.
ABCya
Ab Cya: Prime Numbers
Number Ninja: Prime Numbers is a fast-action way to practice factors. Act quickly and use your finger or mouse to slice numbers and reduce them to their prime factors. Do not slice a prime number!
Khan Academy
Khan Academy: Prime Factorization
A practice quiz on the prime factorization of numbers. Includes hints.
Other
Help With Fractions: The Greatest Common Factor
Two different methods of finding the greatest common factor are explained at this one page website. It is very easy to follow the step by step directions.
Mangahigh
Mangahigh: Number: Prime Factoring
Explore prime factors and what the missing exponent could be.
Mathigon
Mathigon: Math Foundations: Divisibility and Primes: Prime Numbers
This lesson focuses on prime numbers, numbers that can only be divided by one and itself. It explains the Fundamental Theorem of Arithmetic and the Sieve of Eratosthenes. Includes practice activities.