A:
Positive:
1 x 212188555 x 42437717 x 303126535 x 60625347 x 451465235 x 90293329 x 644951645 x 12899
Negative:
-1 x -21218855-5 x -4243771-7 x -3031265-35 x -606253-47 x -451465-235 x -90293-329 x -64495-1645 x -12899
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 21,218,855, 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 | 21,218,855 | |
| -1 | -21,218,855 |
When you multiply two negative numbers together, you get a positive number. That means both the positive and negative numbers are factors of 21,218,855.
Example:
1 x 21,218,855 = 21,218,855
and
-1 x -21,218,855 = 21,218,855
Notice both answers equal 21,218,855
With that explanation out of the way, let's continue. Next, we take the number 21,218,855 and divide it by 2:
21,218,855 ÷ 2 = 10,609,427.5
If the quotient is a whole number, then 2 and 10,609,427.5 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 | 21,218,855 | |
| -1 | -21,218,855 |
Now, we try dividing 21,218,855 by 3:
21,218,855 ÷ 3 = 7,072,951.6667
If the quotient is a whole number, then 3 and 7,072,951.6667 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 | 21,218,855 | |
| -1 | -21,218,855 |
Let's try dividing by 4:
21,218,855 ÷ 4 = 5,304,713.75
If the quotient is a whole number, then 4 and 5,304,713.75 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 | 21,218,855 | |
| -1 | 21,218,855 |
If you did it right, you will end up with this table:
| 1 | 5 | 7 | 35 | 47 | 235 | 329 | 1,645 | 12,899 | 64,495 | 90,293 | 451,465 | 606,253 | 3,031,265 | 4,243,771 | 21,218,855 |
| -1 | -5 | -7 | -35 | -47 | -235 | -329 | -1,645 | -12,899 | -64,495 | -90,293 | -451,465 | -606,253 | -3,031,265 | -4,243,771 | -21,218,855 |
Here are some more numbers to try:
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