Q: What are the factor combinations of the number 987,790?

 A:
Positive:   1 x 9877902 x 4938955 x 19755810 x 98779
Negative: -1 x -987790-2 x -493895-5 x -197558-10 x -98779


How do I find the factor combinations of the number 987,790?

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 987,790, 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.

1 987,790
-1 -987,790

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 987,790.

Example:
1 x 987,790 = 987,790
and
-1 x -987,790 = 987,790
Notice both answers equal 987,790

With that explanation out of the way, let's continue. Next, we take the number 987,790 and divide it by 2:

987,790 ÷ 2 = 493,895

If the quotient is a whole number, then 2 and 493,895 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 2 493,895 987,790
-1 -2 -493,895 -987,790

Now, we try dividing 987,790 by 3:

987,790 ÷ 3 = 329,263.3333

If the quotient is a whole number, then 3 and 329,263.3333 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 2 493,895 987,790
-1 -2 -493,895 -987,790

Let's try dividing by 4:

987,790 ÷ 4 = 246,947.5

If the quotient is a whole number, then 4 and 246,947.5 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 2 493,895 987,790
-1 -2 -493,895 987,790
Keep dividing by the next highest number until you cannot divide anymore.

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

1251098,779197,558493,895987,790
-1-2-5-10-98,779-197,558-493,895-987,790

More Examples

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