# How to Determine Common & Uncommon Multiples

By Stefan RobertDetermining the common and uncommon multiples of numbers will require you to begin by prime factoring. Determine the common and uncommon multiples of numbers with help from an expert in computers, with two degrees in both Computer Science and Applied Mathematics, in this free video clip.

### Transcript

Hi, my name's Stefan. Today, I'm gonna be speaking on how to find common and uncommon multiples of numbers. Let's take for instance the numbers 6 and 9. Now what you would do is you would prime factor it, in this case you'd get 2, times 3, and over here you would get 3 time 3. Now I would put these two prime factors next to each other, so I would get 2 time 3, and then I would put the prime factors of the 9 down here, and that's 3 times 3. We notice here that they both share the 3 here, so that cancels, so all of the common multiples of these two numbers will be 2, take this number, times 3, and then take this number here, times 3. So this is 6 time 3, and that's 18. So, all of the common multiples will 18 times any number n. N meaning 1, 2, 3, 4, 5, and so on. 18 times any n natural number will be a common multiple of 6 and 9. And that's how you find common multiples.