If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

## Pre-algebra

### Course: Pre-algebra>Unit 1

Lesson 1: Factors and multiples

# Understanding factor pairs

Use multiplication and an understanding of area to identify factor pairs for 6 and 16. Created by Sal Khan.

## Want to join the conversation?

• Do you have to memorize the multipication table to get good at factor pairs?
• Yes, memorizing the multiplication table helps you get good at factor pairs. If you don’t have the multiplication table fully memorized, you can use strategies to help you with forgotten facts. Example: suppose you know that 7x7 is 49 but you forget 7x8. You can just add 49+7 to get 56.

There are also some tests you can use, to find factors.

If the last digit is 0, 2, 4, 6, or 8, then 2 is a factor.

If the digits add to a multiple of 3, then 3 is a factor.

If the last two digits form a multiple or 4, then 4 is a factor.

If the last digit is 0 or 5, then 5 is a factor.

If 2 and 3 are factors, then so is 6.

If the last three digits form a multiple of 8, then 8 is a factor.

If the digits add to a multiple of 9, then 9 is a factor.

If the last digit is 0, then 10 is a factor.

Have a blessed, wonderful day!
• is 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 25, 30, 50, 60, 75, 100, 150 and 300 is a factor of 300 does that make sense?
• Yes, all of those numbers are factors of 300.
• Still do not understand factor pairs
• me niether and im 56 years old
• can i get 10 up votes
• maybe.... i'll upvote U if U upvote me on "can there be three factors in a factor pair?"
• Video transcript

- What we're going to do in this video is talk about factors and factor pairs. Now when we talk about factors, these are really numbers that can be multiplied together to make some number. So, for example, if I were to talk about factors of six, I could multiply two times three to get six and so we would say that two and three are factors of six. In fact we would also say that two and three is a factor pair for six 'cause when I multiply those two I can get six. Now to think about all of the different factor pairs for a number we could think about it in terms of area. How can we make a rectangle with area six? Well you could do it if it's two units by three units. So it could look something like this, I'll just hand draw it. So let's say it has, so let's say our rectangle looks like this. So it has two rows and then three columns and lets say these all have equal area, it's hand drawn but you can see that the area here would be two times three, which would be equal to six square units. Now, what if, what are other
• How can I remember which is a Multiple and which is a Factor?
• a multiple is the answer (20 is a multiple of 5 times 4) 5 times 4 = 20
• can i get 10 up votes
• can there be three factors in a factor pair?
• Well, they're called pairs...
It's easiest as a pair because if you know a factor of a number, you can just divide the number by the factor to get another factor.

Anyway, you could have a factor triplet if you broke one of the 2 factors in the pair into 2 smaller factors haha
This leads on to the idea of prime factorisation, which is quite interesting.
(1 vote)
• ummm I am guessing you people in 5th grade