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### Course: Class 6 (Old)>Unit 3

Lesson 1: Factors and multiples

# Finding factors and multiples

Sal uses divisibility rules to determine if numbers are factors of 154 and then finds multiples of 14. Created by Sal Khan.

## Want to join the conversation?

• what is a multiple? can someone please clarify the difference between a multiple and a factor?
• Multiples and factors are opposite terms.
Multiplies of a number are the numbers that appear when you create a multiplication table for a number. For example:
Multiples of 5 are: 5, 10, 15, 20, 25, 30, 35, 40, etc.
Each multiple is created by multiply 5 times some other number.

Factors are the numbers used to create a multiple.
Factors of 15 are:
3 and 5 because 3 x 5 = 15
1 and 15 because 1 x 15 = 15

Hope this helps.
• What is a factor and what is a multiple?
• factor- a number or quantity that when multiplied with another produces a given number or expression.
multiple-a number that can be divided by another number without a remainder.
• is there an easier way to do this?
• There are a lot of tricks you can use, as Sal does in most of these videos. If you search up divisibility tricks you might find some!
• I still do not understand factors can someone pls explain?
• A factor is one of the numbers in division - the answer is called a "product" while the numbers being multiplied together are called "factors."
• i have a hard time knowing the difference between factors and multiples.
• Factor is a whole number which you can divide or get by dividing a certain number with while a multiple is a whole number you can get by multiplying a certain number.

For example: Let's have a certain number 18.
It's factors are:
1, 2, 3, 9, 18

While it's multiples are:
18, 36, 54, 72, 90 ... and so on.

Hope this helps.
• how do I know if a number is divisible by 7?
• To check if a number is evenly divisible b 7: Take the last digit of a number, double it (x2). Then subtract the result from the rest of the number. I f the resulting number is evenly divisible by 7 so is the original number OR SIMPLY DIVIDE IT AND SEE IN SHORT
• When the number can be divided by 2 and 7 can then be concluded that the number can also be divided by 14? Thanks in advance!
• Why does the trick of adding the numbers of the multiple not work for 5? The multiple 154 comes out to 10, so the factor 5 should be a factor of 154. Why is it not a factor?
• Good question!
One way to see why the digit addition doesn't work for `5`:
Listing the multiples of `5`, notice what happens when you sum their digits.
5 -> 5
10 -> 1
15 -> 6
20 -> 2
25 -> 7
30 -> 3
The sum of digits doesn't really have any meaningful pattern to it.

However, you can see that the ones digit of all the multiples is either `5` or `0`, indicating to us the divisibility rule for `5`: The ones digit is `5` or `0`.
We can then tell that `5` is not a factor of `154` - the ones digit of `154` is `4`.

Happy learning!
• is there a ezer way to do this 🤔