A:
Positive:
1 x 213805455 x 427610931 x 689695155 x 137939271 x 78895509 x 420051355 x 157792545 x 8401
Negative:
-1 x -21380545-5 x -4276109-31 x -689695-155 x -137939-271 x -78895-509 x -42005-1355 x -15779-2545 x -8401
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 21,380,545, it is easier to work with a table - it's called factoring from the outside in.
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 | 21,380,545 | |
| -1 | -21,380,545 |
When you multiply two negative numbers together, you get a positive number. That means both the positive and negative numbers are factors of 21,380,545.
Example:
1 x 21,380,545 = 21,380,545
and
-1 x -21,380,545 = 21,380,545
Notice both answers equal 21,380,545
With that explanation out of the way, let's continue. Next, we take the number 21,380,545 and divide it by 2:
21,380,545 ÷ 2 = 10,690,272.5
If the quotient is a whole number, then 2 and 10,690,272.5 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 | 21,380,545 | |
| -1 | -21,380,545 |
Now, we try dividing 21,380,545 by 3:
21,380,545 ÷ 3 = 7,126,848.3333
If the quotient is a whole number, then 3 and 7,126,848.3333 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 | 21,380,545 | |
| -1 | -21,380,545 |
Let's try dividing by 4:
21,380,545 ÷ 4 = 5,345,136.25
If the quotient is a whole number, then 4 and 5,345,136.25 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 | 21,380,545 | |
| -1 | 21,380,545 |
If you did it right, you will end up with this table:
| 1 | 5 | 31 | 155 | 271 | 509 | 1,355 | 2,545 | 8,401 | 15,779 | 42,005 | 78,895 | 137,939 | 689,695 | 4,276,109 | 21,380,545 |
| -1 | -5 | -31 | -155 | -271 | -509 | -1,355 | -2,545 | -8,401 | -15,779 | -42,005 | -78,895 | -137,939 | -689,695 | -4,276,109 | -21,380,545 |
Here are some more numbers to try:
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