We look at the division of 15964009 by 991 
We want to divide 15964009 by 991.

Going ahead to step 1:
If we divide 1 by 991, we get 0 and a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Grab the next digit (5) from the dividend, add it to 1, then carry on: 15 / 991

Step 2:
The number 991 fits into 15 0 times, leaving a remainder of 15.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 15, we get 15.
Bring next digit (9) of the dividend behind the 15 and repeat the process: 159 / 991

Going ahead to step 3:
If we divide 159 by 991, we get 0 and a remainder of 159.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 159 and we're left with 159.
Append the next digit (6) from the dividend to 159 and continue with: 1596 / 991

Advancing to step 4:
1596 divided by 991 is 1 with a remainder of 605.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we subtract 991 from 1596, we get 605.
Bring next digit (4) of the dividend behind the 605 and repeat the process: 6054 / 991

Moving on to step 5:
6054 divided by 991 is 6 with a remainder of 108.
Use 6 as the next digit of our solution. 
Result so far: 16.0
If we take 5946 away from 6054, we end up with 108.
Include the next digit (0) from the dividend after 108, then repeat: 1080 / 991

On to step 6:
991 goes into 1080 1 times with a remainder of 89.
The next digit of our result is 1. 
Result so far: 161.0
Subtracting 991 from 1080 leaves us with 89.
Include the next digit (0) from the dividend after 89, then repeat: 890 / 991

Advancing to step 7:
991 can be fit into 890 0 times, resulting in a remainder of 890.
Use 0 as the next digit of our solution. 
Result so far: 1610.0
The remainder is 890 after subtracting 0 from 890.
Take the next digit (9) from the dividend and append it to 890, then repeat: 8909 / 991

Going ahead to step 8:
If we divide 8909 by 991, we get 8 and a remainder of 981.
Record the quotient 8 as the next digit in the result. 
Result so far: 16108.0
Deduct 7928 from 8909 and we're left with 981.
Since there are no more digits in the dividend, we add a zero to the remainder making it 9810, and continue the process.

Step 9:
991 goes into 9810 9 times with a remainder of 891.
Put 9 as the next digit of the answer. 
Result so far: 16108.9
The remainder is 891 after subtracting 8919 from 9810.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8910, and continue the process.

Moving on to step 10:
The number 991 fits into 8910 8 times, leaving a remainder of 982.
Record the quotient 8 as the next digit in the result. 
Result so far: 16108.98
Subtracting 7928 from 8910 leaves us with 982.
Since there are no more digits in the dividend, we add a zero to the remainder making it 9820, and continue the process.

Going ahead to step 11:
991 goes into 9820 9 times with a remainder of 901.
Write down 9 as next digit of the result. 
Result so far: 16108.989
Subtracting 8919 from 9820 leaves us with 901.
Since there are no more digits in the dividend, we add a zero to the remainder making it 9010, and continue the process.

Moving on to step 12:
When dividing 9010 by 991, we get 9 with a remainder of 91.
Record the quotient 9 as the next digit in the result. 
Result so far: 16108.9899
Subtracting 8919 from 9010 leaves us with 91.
Since there are no more digits in the dividend, we add a zero to the remainder making it 910, and continue the process.

The final outcome is 16108.9899, with a leftover of 0.00091.