A:
Positive:
1 x 2138797713 x 164522919 x 1125683131 x 163267247 x 86591661 x 323571703 x 125592489 x 8593
Negative:
-1 x -21387977-13 x -1645229-19 x -1125683-131 x -163267-247 x -86591-661 x -32357-1703 x -12559-2489 x -8593
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 21,387,977, 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 | 21,387,977 | |
| -1 | -21,387,977 |
When you multiply two negative numbers together, you get a positive number. That means both the positive and negative numbers are factors of 21,387,977.
Example:
1 x 21,387,977 = 21,387,977
and
-1 x -21,387,977 = 21,387,977
Notice both answers equal 21,387,977
With that explanation out of the way, let's continue. Next, we take the number 21,387,977 and divide it by 2:
21,387,977 ÷ 2 = 10,693,988.5
If the quotient is a whole number, then 2 and 10,693,988.5 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 | 21,387,977 | |
| -1 | -21,387,977 |
Now, we try dividing 21,387,977 by 3:
21,387,977 ÷ 3 = 7,129,325.6667
If the quotient is a whole number, then 3 and 7,129,325.6667 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 | 21,387,977 | |
| -1 | -21,387,977 |
Let's try dividing by 4:
21,387,977 ÷ 4 = 5,346,994.25
If the quotient is a whole number, then 4 and 5,346,994.25 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 | 21,387,977 | |
| -1 | 21,387,977 |
If you did it right, you will end up with this table:
| 1 | 13 | 19 | 131 | 247 | 661 | 1,703 | 2,489 | 8,593 | 12,559 | 32,357 | 86,591 | 163,267 | 1,125,683 | 1,645,229 | 21,387,977 |
| -1 | -13 | -19 | -131 | -247 | -661 | -1,703 | -2,489 | -8,593 | -12,559 | -32,357 | -86,591 | -163,267 | -1,125,683 | -1,645,229 | -21,387,977 |
Here are some more numbers to try:
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