Factors of 21
So you need to find the factors of 21 do you? In this quick guide we'll describe what the factors of 21 are, how you find them and list out the factor pairs of 21 for you to prove the calculation works. Let's dive in!
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Factors of 21 Definition
When we talk about the factors of 21, what we really mean is all of the positive and negative integers (whole numbers) that can be evenly divided into 21. If you were to take 21 and divide it by one of its factors, the answer would be another factor of 21.
Let's look at how to find all of the factors of 21 and list them out.
How to Find the Factors of 21
We just said that a factor is a number that can be divided equally into 21. So the way you find and list all of the factors of 21 is to go through every number up to and including 21 and check which numbers result in an even quotient (which means no decimal place).
Doing this by hand for large numbers can be time consuming, but it's relatively easy for a computer program to do it. Our calculator has worked this out for you. Here are all of the factors of 21:
- 21 ÷ 1 = 21
- 21 ÷ 3 = 7
- 21 ÷ 7 = 3
- 21 ÷ 21 = 1
All of these factors can be used to divide 21 by and get a whole number. The full list of positive factors for 21 are:
1, 3, 7, and 21
Negative Factors of 21
Technically, in math you can also have negative factors of 21. If you are looking to calculate the factors of a number for homework or a test, most often the teacher or exam will be looking for specifically positive numbers.
However, we can just flip the positive numbers into negatives and those negative numbers would also be factors of 21:
-1, -3, -7, and -21
How Many Factors of 21 Are There?
As we can see from the calculations above there are a total of 4 positive factors for 21 and 4 negative factors for 21 for a total of 8 factors for the number 21.
There are 4 positive factors of 21 and 4 negative factors of 21. Wht are there negative numbers that can be a factor of 21?
Factor Pairs of 21
A factor pair is a combination of two factors which can be multiplied together to equal 21. For 21, all of the possible factor pairs are listed below:
- 1 x 21 = 21
- 3 x 7 = 21
We have also written a guide that goes into a little more detail about the factor pairs for 21 in case you are interested!
Just like before, we can also list out all of the negative factor pairs for 21:
- -1 x -21 = 21
- -3 x -7 = 21
Notice in the negative factor pairs that because we are multiplying a minus with a minus, the result is a positive number.
So there you have it. A complete guide to the factors of 21. You should now have the knowledge and skills to go out and calculate your own factors and factor pairs for any number you like.
Feel free to try the calculator below to check another number or, if you're feeling fancy, grab a pencil and paper and try and do it by hand. Just make sure to pick small numbers!
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"Factors of 21". VisualFractions.com. Accessed on December 6, 2021. http://visualfractions.com/calculator/factors/factors-of-21/.
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