Q: What are the factor combinations of the number 21,084?

 A:
Positive:   1 x 210842 x 105423 x 70284 x 52716 x 35147 x 301212 x 175714 x 150621 x 100428 x 75342 x 50284 x 251
Negative: -1 x -21084-2 x -10542-3 x -7028-4 x -5271-6 x -3514-7 x -3012-12 x -1757-14 x -1506-21 x -1004-28 x -753-42 x -502-84 x -251


How do I find the factor combinations of the number 21,084?

Unfortunately, there's not simple formula to identifying all of the factors of a number and it can be a tedious process when trying to identify the divisors of larger numbers. To find the factor combinations of the number 21,084, it is easier to work with a table - it's called factoring from the outside in.

Outside in Factoring

We start by creating a table and writing 1 on the left side and then the number we're trying to find the factors for on the right side in a table. Then, below that, write the numbers as a negative as well.

1 21,084
-1 -21,084

Why are the negative numbers included?

When you multiply two negative numbers together, you get a positive number. That means both the positive and negative numbers are factors of 21,084.

Example:
1 x 21,084 = 21,084
and
-1 x -21,084 = 21,084
Notice both answers equal 21,084

With that explanation out of the way, let's continue. Next, we take the number 21,084 and divide it by 2:

21,084 ÷ 2 = 10,542

If the quotient is a whole number, then 2 and 10,542 are factors. In this case, the quotient is a whole number. Write them in the table inside the other two factors like the below example. Don't forget to write the negative numbers too!

Here is what our table should look like at this step:

1 2 10,542 21,084
-1 -2 -10,542 -21,084

Now, we try dividing 21,084 by 3:

21,084 ÷ 3 = 7,028

If the quotient is a whole number, then 3 and 7,028 are factors. In this case, the quotient is a whole number. Write them in the table inside the other two factors like the below example. Don't forget to write the negative numbers too!

Here is what our table should look like at this step:

1 2 3 7,028 10,542 21,084
-1 -2 -3 -7,028 -10,542 -21,084

Let's try dividing by 4:

21,084 ÷ 4 = 5,271

If the quotient is a whole number, then 4 and 5,271 are factors. In this case, the quotient is a whole number. Write them in the table inside the other two factors like the below example. Don't forget to write the negative numbers too!

Here is what our table should look like at this step:

1 2 3 4 5,271 7,028 10,542 21,084
-1 -2 -3 -4 -5,271 -7,028 -10,542 21,084
Keep dividing by the next highest number until you cannot divide anymore.

If you did it right, you will end up with this table:

1234671214212842842515027531,0041,5061,7573,0123,5145,2717,02810,54221,084
-1-2-3-4-6-7-12-14-21-28-42-84-251-502-753-1,004-1,506-1,757-3,012-3,514-5,271-7,028-10,542-21,084

More Examples

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