A:
Positive:
1 x 211052155 x 4221043103 x 204905107 x 197245383 x 55105515 x 40981535 x 394491915 x 11021
Negative:
-1 x -21105215-5 x -4221043-103 x -204905-107 x -197245-383 x -55105-515 x -40981-535 x -39449-1915 x -11021
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 21,105,215, 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 | 21,105,215 | |
| -1 | -21,105,215 |
When you multiply two negative numbers together, you get a positive number. That means both the positive and negative numbers are factors of 21,105,215.
Example:
1 x 21,105,215 = 21,105,215
and
-1 x -21,105,215 = 21,105,215
Notice both answers equal 21,105,215
With that explanation out of the way, let's continue. Next, we take the number 21,105,215 and divide it by 2:
21,105,215 ÷ 2 = 10,552,607.5
If the quotient is a whole number, then 2 and 10,552,607.5 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 | 21,105,215 | |
| -1 | -21,105,215 |
Now, we try dividing 21,105,215 by 3:
21,105,215 ÷ 3 = 7,035,071.6667
If the quotient is a whole number, then 3 and 7,035,071.6667 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 | 21,105,215 | |
| -1 | -21,105,215 |
Let's try dividing by 4:
21,105,215 ÷ 4 = 5,276,303.75
If the quotient is a whole number, then 4 and 5,276,303.75 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 | 21,105,215 | |
| -1 | 21,105,215 |
If you did it right, you will end up with this table:
| 1 | 5 | 103 | 107 | 383 | 515 | 535 | 1,915 | 11,021 | 39,449 | 40,981 | 55,105 | 197,245 | 204,905 | 4,221,043 | 21,105,215 |
| -1 | -5 | -103 | -107 | -383 | -515 | -535 | -1,915 | -11,021 | -39,449 | -40,981 | -55,105 | -197,245 | -204,905 | -4,221,043 | -21,105,215 |
Here are some more numbers to try:
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