Q: What are the factor combinations of the number 21,188,768?

 A:
Positive:   1 x 211887682 x 105943844 x 52971928 x 264859616 x 132429832 x 662149
Negative: -1 x -21188768-2 x -10594384-4 x -5297192-8 x -2648596-16 x -1324298-32 x -662149


How do I find the factor combinations of the number 21,188,768?

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 21,188,768, 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 21,188,768
-1 -21,188,768

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 21,188,768.

Example:
1 x 21,188,768 = 21,188,768
and
-1 x -21,188,768 = 21,188,768
Notice both answers equal 21,188,768

With that explanation out of the way, let's continue. Next, we take the number 21,188,768 and divide it by 2:

21,188,768 ÷ 2 = 10,594,384

If the quotient is a whole number, then 2 and 10,594,384 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 10,594,384 21,188,768
-1 -2 -10,594,384 -21,188,768

Now, we try dividing 21,188,768 by 3:

21,188,768 ÷ 3 = 7,062,922.6667

If the quotient is a whole number, then 3 and 7,062,922.6667 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 10,594,384 21,188,768
-1 -2 -10,594,384 -21,188,768

Let's try dividing by 4:

21,188,768 ÷ 4 = 5,297,192

If the quotient is a whole number, then 4 and 5,297,192 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 5,297,192 10,594,384 21,188,768
-1 -2 -4 -5,297,192 -10,594,384 21,188,768
Keep dividing by the next highest number until you cannot divide anymore.

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

12481632662,1491,324,2982,648,5965,297,19210,594,38421,188,768
-1-2-4-8-16-32-662,149-1,324,298-2,648,596-5,297,192-10,594,384-21,188,768

More Examples

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