Khan Academy: Arithmetic and Pre Algebra: Prime Factorization

Older elementary students will appreciate how clearly Sal explains how to find the prime factorization of 75. He shows the complete process, taking note of numbers that are, and are not primes, and why.

Deepen the number sense of young mathematicians by exploring the process of prime factorization. Follow along with this step-by-step presentation that explains how factor trees are used to break a composite number down into its prime...

A factor tree? What's a factor tree? A tree of factors? A factor tree is a method use to do the prime factorization of an integer. It's not complicated. Watch the teacher as she explains the steps and shows how to write the answer as a...

Here's a quick review on how to use a prime factor tree to find the greatest common factor of two numbers. This is one of the simplest ways to find the greatest common factor. So watch this video to get a refresher on how to do prime...

This video shows how to find the least common multiple of three numbers using lists of multiples or prime factorization. Practice problems are available. [5:23]

This video shows several examples of addition with up to four-digit numbers. Practice problems are available. [8:57]

A video covering a review of subtraction using a number line, followed by subtraction of numbers up to three-digits by using borrowing and regrouping. Practice problems available. [18:26]

This video shows how to compare two fractions using a several methods. Practice problems are available. [7:08]

This video explains how to find the reciprocal of a mixed number. [1:41]

Two-digit by two-digit multiplication demonstrated through example in this short video. Practice problems are available. [3:18]