Q: What are the factor combinations of the number 31,128?

 A:
Positive:   1 x 311282 x 155643 x 103764 x 77826 x 51888 x 389112 x 259424 x 1297
Negative: -1 x -31128-2 x -15564-3 x -10376-4 x -7782-6 x -5188-8 x -3891-12 x -2594-24 x -1297


How do I find the factor combinations of the number 31,128?

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 31,128, 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 31,128
-1 -31,128

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 31,128.

Example:
1 x 31,128 = 31,128
and
-1 x -31,128 = 31,128
Notice both answers equal 31,128

With that explanation out of the way, let's continue. Next, we take the number 31,128 and divide it by 2:

31,128 ÷ 2 = 15,564

If the quotient is a whole number, then 2 and 15,564 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 15,564 31,128
-1 -2 -15,564 -31,128

Now, we try dividing 31,128 by 3:

31,128 ÷ 3 = 10,376

If the quotient is a whole number, then 3 and 10,376 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 10,376 15,564 31,128
-1 -2 -3 -10,376 -15,564 -31,128

Let's try dividing by 4:

31,128 ÷ 4 = 7,782

If the quotient is a whole number, then 4 and 7,782 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 7,782 10,376 15,564 31,128
-1 -2 -3 -4 -7,782 -10,376 -15,564 31,128
Keep dividing by the next highest number until you cannot divide anymore.

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

12346812241,2972,5943,8915,1887,78210,37615,56431,128
-1-2-3-4-6-8-12-24-1,297-2,594-3,891-5,188-7,782-10,376-15,564-31,128

More Examples

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