Prime numbers | Factors and multiples | Pre-Algebra | Khan Academy

Prime and Composite Numbers

Prime Numbers - Sieve of Eratosthenes

Try out this guided activity and complete the Sieve of Eratosthenes yourself.

Prime and Composite Numbers

Math Antics - Prime Factorization

Recognizing prime and composite numbers (4th grade)

Prime Numbers and Divisibility Rules

Try out these games:
Number Ninjas (prime factors)
Fruit Splat (prime numbers)

Quiz Yourself

Prime Factorization Review

Prime Factorization

Check out Khan Academy's page for practice and more videos on this topic.

Prime Factorization

Watch the video above as a refresher on prime factorization.  You can watch more and try a few practice problems on Khan's website.  Try out a few quizzes on prime factorization and exponents.
Quiz #1
Quiz #2