A:
Positive:
1 x 721007217 x 1030010311 x 655461177 x 936373103 x 700007721 x 1000011133 x 636377931 x 9091
Negative:
-1 x -72100721-7 x -10300103-11 x -6554611-77 x -936373-103 x -700007-721 x -100001-1133 x -63637-7931 x -9091
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 72,100,721, 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 | 72,100,721 | |
| -1 | -72,100,721 |
When you multiply two negative numbers together, you get a positive number. That means both the positive and negative numbers are factors of 72,100,721.
Example:
1 x 72,100,721 = 72,100,721
and
-1 x -72,100,721 = 72,100,721
Notice both answers equal 72,100,721
With that explanation out of the way, let's continue. Next, we take the number 72,100,721 and divide it by 2:
72,100,721 ÷ 2 = 36,050,360.5
If the quotient is a whole number, then 2 and 36,050,360.5 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 | 72,100,721 | |
| -1 | -72,100,721 |
Now, we try dividing 72,100,721 by 3:
72,100,721 ÷ 3 = 24,033,573.6667
If the quotient is a whole number, then 3 and 24,033,573.6667 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 | 72,100,721 | |
| -1 | -72,100,721 |
Let's try dividing by 4:
72,100,721 ÷ 4 = 18,025,180.25
If the quotient is a whole number, then 4 and 18,025,180.25 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 | 72,100,721 | |
| -1 | 72,100,721 |
If you did it right, you will end up with this table:
| 1 | 7 | 11 | 77 | 103 | 721 | 1,133 | 7,931 | 9,091 | 63,637 | 100,001 | 700,007 | 936,373 | 6,554,611 | 10,300,103 | 72,100,721 |
| -1 | -7 | -11 | -77 | -103 | -721 | -1,133 | -7,931 | -9,091 | -63,637 | -100,001 | -700,007 | -936,373 | -6,554,611 | -10,300,103 | -72,100,721 |
Here are some more numbers to try:
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