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# Online games for prime factorization, factors, GCF, and LCM

This is an annotated and hand-picked list of online games, activities, quizzes, and worksheets for factors, prime factorization, greatest common factor, and least common multiple (number theory topics). I have tried to gather a variety of resources and have personally checked out each website, to make sure it is truly useful for my site visitors!

## Factors and prime factorization

Arrays and factors
Drag rectangles to show the factorizations of a given number.
wwwshodor.org/interactivate/activities/factors2/index.html.

Factor Game
A fun, interactive game where you practice divisibility among numbers 1-100. You can play against the computer or against a friend.
illuminations.nctm.org/Activity.aspx?id=4134

Factor Feeder
Eat factors of the given number, and avoid numbers that are not factors of the given number in this Pacman-style game. Use Arrow Keys to move.
hoodamath.com/games/factorfeeder.php

Sliding Tile Factorization Game
Slide a number over another to capture it, if it is a factor of the other. Number 1 is only supposed to be used to capture a prime number.
www.visualmathlearning.com/Games/sliding_factors.html

Octopus Factors
Move counters up the legs of an octopus but only when the number on the circle is a multiple of the number on the card.
www.counton.org/games/map-numbers/octopus/

Factors Millionaire Game
A millionaire game where the questions have to do with factors, prime numbers, and the greatest common factor.
www.math-play.com/Factors-Millionaire/Factors-Millionaire.html

Not a Factor
Choose a number that is NOT a factor of the given number.
www.helpingwithmath.com/resources/games/target_factors01/not_factor.html

Factorization Forest
For each number you factorize, you'll get to grow a tree in your forest! You can choose between 6 different trees, also.
mrnussbaum.com/forest/

Factor Trees at Math Playground
Factor numbers to their prime factors using an interactive factor tree, or find the GCF and LCM of numbers.
www.mathplayground.com/factortrees.html

An Interactive Sieve of Eratosthenes
To find all prime numbers below a given number, use a sieve of Eratosthenes to "weed out" all the composite numbers.
www.cut-the-knot.org/Curriculum/Arithmetic/Eratosthenes.shtml

An Another interactive sieve of Eratosthenes
Click on a number to remove its multiples from the grid.
nlvm.usu.edu/en/nav/frames_asid_158_g_3_t_1.html?open=instructions

MathGoodies Interactive Factor Tree Game
Type in a missing number to the factor tree, and the program will find the other factor, and continue drawing the tree as needed.
www.mathgoodies.com/factors/prime_factors.html

Snake
Eat factors, multiples, and prime numbers in this remake of the classic game.

Math Mammoth Multiplication & Division 3
A self-teaching worktext for 5th grade that covers multi-digit multiplication, long division, problem solving, simple equations, ratios, divisibility, and factoring. Available as a download (\$7.40) and also as a printed copy.
www.mathmammoth.com/multiplication_division_3.php

Free workheets for prime factorization
Generate free, printable worksheets for prime factorization or for finding all the factors of a given number. Customize the worksheets in various ways (difficulty level, spacing, font size, number of problems.)
/worksheets/factoring.php

Product game
For two players; each selects a factor, computer colors the product - who gets four in row wins.
illuminations.nctm.org/ActivityDetail.aspx?ID=29

Primes, Factors and Divisibility—Explorer at CountOn.org
Lessons explaining divisibility tests, primes, and factors.
www.counton.org/explorer/primes

So-Soo-Yoo®
A fun board game that helps children practice factors, factoring, and multiplication at the same time. Price \$34.
teruen.com

Prime Numbers as Building Blocks - Euclid's greatest discovery
A short video about the fundamental theorem of arithmetic: that each composite number has a unique prime factorization.

Prime Number Calculator
This calculator tests if a number is a prime, and tells you its smallest divisor if it is not prime.
www.basic-mathematics.com/prime-number-calculator.html

## Greatest Common Factor and Least Common Multiple

Fruit Shoot - Greatest Common Factor
Shoot the fruit that has the greatest common factor of two given numbers. Three levels and two different speeds.
www.sheppardsoftware.com/mathgames/fractions/GreatestCommonFactor.htm

Fruit Shoot - Least Common Multiple
Shoot the fruit that has the least common multiple of two given numbers. Three levels and two different speeds.
www.sheppardsoftware.com/mathgames/fractions/LeastCommonMultiple.htm

Factors and Multiples Jeopardy Game
A jeopardy game where the questions have to do with factors, multiples, prime factorization, GCF, and LCM.
www.math-play.com/Factors-and-Multiples-Jeopardy/Factors-and-Multiples-Jeopardy.html

Factors, LCM, and GCF - activity from Math Playground
Choose 'Find the prime factorization of 2 numbers, GCF, and LCM'. First, you find the prime factorization of two different numbers, using the factor tree. Once that is done, the activity shows you a Venn diagram. Drag the factors of the two numbers in the correct areas, then figure out their GFC and LCM.
www.mathplayground.com/factortrees.html

Free workheets for greatest common factor and least common multiple
Generate free, printable worksheets for GCF and LCM. Customize the worksheets in various ways (choose number range, font size, etc.)
/worksheets/GCF_LCM.php

Least common multiple tutorial
An animated tutorial and exercises for the Least common multiple from e-learning for Kids.
e-learningforkids.org/Courses/EN/M1105

Greatest Common Factor - That Quiz
10-question quiz, not timed, difficulty level 5 (medium). You can also change the parameters to your liking.
www.thatquiz.org/tq-r/?-j2-l5-p0

Least Common Multiple - That Quiz
10-question quiz, not timed, difficulty level 5 (medium). You can also change the parameters to your liking.
www.thatquiz.org/tq-r/?-j4-l5-p0

GCF and LCM Quiz
10-question quiz, not timed, difficulty level 5 (medium). You can also change the parameters to your liking.
www.thatquiz.org/tq-r/?-j4-l5-p0

Math Problems with LCM & GCF
A quiz of 10 word problems involving the usage of the greatest common factor and the least common multiple.
www.funtrivia.com/playquiz/quiz2715661f17598.html

Greatest Common Factor - Activity from Glencoe
First, the activity asks you to click on all the factors of two numbers (which represent how many apples and oranges there are to bag). Then you find the GFC of them. Next, it gives you practice problems for finding all factors of a number, finding common factors of two numbers, and finding the GCF of two numbers.
www.glencoe.com/sites/common_assets/mathematics/mc1/cim/chapter_04/M1_06/M1_06_dev_100.html

Snowball Fight! - Least Common Multiple (LCM)
Multiple-choice questions on the LCM of two numbers - when you click the right answer, a snowball flies into a kid.
www.fun4thebrain.com/beyondfacts/lcmsnowball.html

Pyramid Math
This includes games for GCF, LCM, exponents, and square roots. The question to solve appears in the right, under 'example'. Choose the triangular tile with the correct answer, and drag it to the solution vase. Includes easy and hard levels, timed and non-timed versions.
www.mathnook.com/math/pyramidmath.html