Q: What are the factor combinations of the number 209?

 A:
Positive:   1 x 20911 x 19
Negative: -1 x -209-11 x -19


How do I find the factor combinations of the number 209?

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 209, 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.

1 209
-1 -209

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 209.

Example:
1 x 209 = 209
and
-1 x -209 = 209
Notice both answers equal 209

With that explanation out of the way, let's continue. Next, we take the number 209 and divide it by 2:

209 ÷ 2 = 104.5

If the quotient is a whole number, then 2 and 104.5 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:

1 209
-1 -209

Now, we try dividing 209 by 3:

209 ÷ 3 = 69.6667

If the quotient is a whole number, then 3 and 69.6667 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:

1 209
-1 -209

Let's try dividing by 4:

209 ÷ 4 = 52.25

If the quotient is a whole number, then 4 and 52.25 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:

1 209
-1 209
Keep dividing by the next highest number until you cannot divide anymore.

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

11119209
-1-11-19-209

More Examples

Here are some more numbers to try:

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