Q: What are the factor combinations of the number 31,172?

 A:
Positive:   1 x 311722 x 155864 x 7793
Negative: -1 x -31172-2 x -15586-4 x -7793


How do I find the factor combinations of the number 31,172?

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 31,172, 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 31,172
-1 -31,172

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 31,172.

Example:
1 x 31,172 = 31,172
and
-1 x -31,172 = 31,172
Notice both answers equal 31,172

With that explanation out of the way, let's continue. Next, we take the number 31,172 and divide it by 2:

31,172 ÷ 2 = 15,586

If the quotient is a whole number, then 2 and 15,586 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 15,586 31,172
-1 -2 -15,586 -31,172

Now, we try dividing 31,172 by 3:

31,172 ÷ 3 = 10,390.6667

If the quotient is a whole number, then 3 and 10,390.6667 are factors. In this case, the quotient is not a whole number. Don't write anything down and try the next divisor.

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

1 2 15,586 31,172
-1 -2 -15,586 -31,172

Let's try dividing by 4:

31,172 ÷ 4 = 7,793

If the quotient is a whole number, then 4 and 7,793 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 4 7,793 15,586 31,172
-1 -2 -4 -7,793 -15,586 31,172
Keep dividing by the next highest number until you cannot divide anymore.

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

1247,79315,58631,172
-1-2-4-7,793-15,586-31,172

More Examples

Here are some more numbers to try:

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