A:
Positive:
1 x 2157815155 x 4315630323 x 9381805115 x 1876361139 x 1552385695 x 3104773197 x 6749513499 x 15985
Negative:
-1 x -215781515-5 x -43156303-23 x -9381805-115 x -1876361-139 x -1552385-695 x -310477-3197 x -67495-13499 x -15985
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 215,781,515, 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 | 215,781,515 | |
| -1 | -215,781,515 |
When you multiply two negative numbers together, you get a positive number. That means both the positive and negative numbers are factors of 215,781,515.
Example:
1 x 215,781,515 = 215,781,515
and
-1 x -215,781,515 = 215,781,515
Notice both answers equal 215,781,515
With that explanation out of the way, let's continue. Next, we take the number 215,781,515 and divide it by 2:
215,781,515 ÷ 2 = 107,890,757.5
If the quotient is a whole number, then 2 and 107,890,757.5 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 | 215,781,515 | |
| -1 | -215,781,515 |
Now, we try dividing 215,781,515 by 3:
215,781,515 ÷ 3 = 71,927,171.6667
If the quotient is a whole number, then 3 and 71,927,171.6667 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 | 215,781,515 | |
| -1 | -215,781,515 |
Let's try dividing by 4:
215,781,515 ÷ 4 = 53,945,378.75
If the quotient is a whole number, then 4 and 53,945,378.75 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 | 215,781,515 | |
| -1 | 215,781,515 |
If you did it right, you will end up with this table:
| 1 | 5 | 23 | 115 | 139 | 695 | 3,197 | 13,499 | 15,985 | 67,495 | 310,477 | 1,552,385 | 1,876,361 | 9,381,805 | 43,156,303 | 215,781,515 |
| -1 | -5 | -23 | -115 | -139 | -695 | -3,197 | -13,499 | -15,985 | -67,495 | -310,477 | -1,552,385 | -1,876,361 | -9,381,805 | -43,156,303 | -215,781,515 |
Here are some more numbers to try:
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