Q: What are the factor combinations of the number 720?

 A:
Positive:   1 x 7202 x 3603 x 2404 x 1805 x 1446 x 1208 x 909 x 8010 x 7212 x 6015 x 4816 x 4518 x 4020 x 3624 x 30
Negative: -1 x -720-2 x -360-3 x -240-4 x -180-5 x -144-6 x -120-8 x -90-9 x -80-10 x -72-12 x -60-15 x -48-16 x -45-18 x -40-20 x -36-24 x -30


How do I find the factor combinations of the number 720?

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 720, 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.

1 720
-1 -720

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 720.

Example:
1 x 720 = 720
and
-1 x -720 = 720
Notice both answers equal 720

With that explanation out of the way, let's continue. Next, we take the number 720 and divide it by 2:

720 ÷ 2 = 360

If the quotient is a whole number, then 2 and 360 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 2 360 720
-1 -2 -360 -720

Now, we try dividing 720 by 3:

720 ÷ 3 = 240

If the quotient is a whole number, then 3 and 240 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 3 240 360 720
-1 -2 -3 -240 -360 -720

Let's try dividing by 4:

720 ÷ 4 = 180

If the quotient is a whole number, then 4 and 180 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 3 4 180 240 360 720
-1 -2 -3 -4 -180 -240 -360 720
Keep dividing by the next highest number until you cannot divide anymore.

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

1234568910121516182024303640454860728090120144180240360720
-1-2-3-4-5-6-8-9-10-12-15-16-18-20-24-30-36-40-45-48-60-72-80-90-120-144-180-240-360-720

More Examples

Here are some more numbers to try:

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