We divide 15991 by 51
We're looking to find how many times 51 goes into 15991.

On to step 1:
51 can be fit into 1 0 times, resulting in a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Take the next digit (5) from the dividend and append it to 1, then repeat: 15 / 51

Let's proceed to step 2:
51 goes into 15 0 times with a remainder of 15.
Use 0 as the next digit of our solution. 
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 / 51

Advancing to step 3:
If we divide 159 by 51, we get 3 and a remainder of 6.
Write down 3 as next digit of the result. 
Result so far: 3.0
The remainder is 6 after subtracting 153 from 159.
Bring next digit (9) of the dividend behind the 6 and repeat the process: 69 / 51

Moving on to step 4:
51 can be fit into 69 1 times, resulting in a remainder of 18.
Put 1 as the next digit of the answer. 
Result so far: 31.0
Subtract 51 from 69 to get 18.
Include the next digit (1) from the dividend after 18, then repeat: 181 / 51

Advancing to step 5:
The number 51 fits into 181 3 times, leaving a remainder of 28.
Write down 3 as next digit of the result. 
Result so far: 313.0
Deduct 153 from 181 and we're left with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

On to step 6:
When dividing 280 by 51, we get 5 with a remainder of 25.
Use 5 as the next digit of our solution. 
Result so far: 313.5
If we subtract 255 from 280, we get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Step 7:
51 can be fit into 250 4 times, resulting in a remainder of 46.
Write down 4 as next digit of the result. 
Result so far: 313.54
Deduct 204 from 250 and we're left with 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Advancing to step 8:
The number 51 fits into 460 9 times, leaving a remainder of 1.
The next digit of our result is 9. 
Result so far: 313.549
Deduct 459 from 460 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

On to step 9:
51 goes into 10 0 times with a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 313.549
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 10:
When dividing 100 by 51, we get 1 with a remainder of 49.
The next digit of our result is 1. 
Result so far: 313.54901
If we subtract 51 from 100, we get 49.
Since there are no more digits in the dividend, we add a zero to the remainder making it 490, and continue the process.

Advancing to step 11:
490 divided by 51 is 9 with a remainder of 31.
The number 9 becomes the next digit in our result. 
Result so far: 313.549019
Deduct 459 from 490 and we're left with 31.
Since there are no more digits in the dividend, we add a zero to the remainder making it 310, and continue the process.

Going ahead to step 12:
The number 51 fits into 310 6 times, leaving a remainder of 4.
Write down 6 as next digit of the result. 
Result so far: 313.5490196
If we subtract 306 from 310, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Moving on to step 13:
51 can be fit into 40 0 times, resulting in a remainder of 40.
Put 0 as the next digit of the answer. 
Result so far: 313.5490196
If we take 0 away from 40, we end up with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

The quotient of the division is 313.5490196, and the remainder is 4e-08.