Q: What are the factor combinations of the number 687,815?

 A:
Positive:   1 x 6878155 x 13756323 x 29905115 x 5981
Negative: -1 x -687815-5 x -137563-23 x -29905-115 x -5981


How do I find the factor combinations of the number 687,815?

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 687,815, 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.

1 687,815
-1 -687,815

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 687,815.

Example:
1 x 687,815 = 687,815
and
-1 x -687,815 = 687,815
Notice both answers equal 687,815

With that explanation out of the way, let's continue. Next, we take the number 687,815 and divide it by 2:

687,815 ÷ 2 = 343,907.5

If the quotient is a whole number, then 2 and 343,907.5 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:

1 687,815
-1 -687,815

Now, we try dividing 687,815 by 3:

687,815 ÷ 3 = 229,271.6667

If the quotient is a whole number, then 3 and 229,271.6667 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:

1 687,815
-1 -687,815

Let's try dividing by 4:

687,815 ÷ 4 = 171,953.75

If the quotient is a whole number, then 4 and 171,953.75 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:

1 687,815
-1 687,815
Keep dividing by the next highest number until you cannot divide anymore.

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

15231155,98129,905137,563687,815
-1-5-23-115-5,981-29,905-137,563-687,815

More Examples

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