We look at the division of 51211015 by 395 
Let's see how many times 395 fits into 51211015.

On to step 1:
The number 395 fits into 5 0 times, leaving a remainder of 5.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Grab the next digit (1) from the dividend, add it to 5, then carry on: 51 / 395

Step 2:
51 divided by 395 is 0 with a remainder of 51.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 51 leaves us with 51.
Take the next digit (2) from the dividend and append it to 51, then repeat: 512 / 395

On to step 3:
The number 395 fits into 512 1 times, leaving a remainder of 117.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Deduct 395 from 512 and we're left with 117.
Grab the next digit (1) from the dividend, add it to 117, then carry on: 1171 / 395

Step 4:
The number 395 fits into 1171 2 times, leaving a remainder of 381.
The number 2 becomes the next digit in our result. 
Result so far: 12.0
If we take 790 away from 1171, we end up with 381.
Include the next digit (1) from the dividend after 381, then repeat: 3811 / 395

Moving on to step 5:
When dividing 3811 by 395, we get 9 with a remainder of 256.
Use 9 as the next digit of our solution. 
Result so far: 129.0
If we subtract 3555 from 3811, we get 256.
Include the next digit (0) from the dividend after 256, then repeat: 2560 / 395

Going ahead to step 6:
2560 divided by 395 is 6 with a remainder of 190.
Record the quotient 6 as the next digit in the result. 
Result so far: 1296.0
Deduct 2370 from 2560 and we're left with 190.
Include the next digit (1) from the dividend after 190, then repeat: 1901 / 395

Step 7:
When dividing 1901 by 395, we get 4 with a remainder of 321.
Use 4 as the next digit of our solution. 
Result so far: 12964.0
If we take 1580 away from 1901, we end up with 321.
Include the next digit (5) from the dividend after 321, then repeat: 3215 / 395

Step 8:
395 can be fit into 3215 8 times, resulting in a remainder of 55.
Use 8 as the next digit of our solution. 
Result so far: 129648.0
Deduct 3160 from 3215 and we're left with 55.
Since there are no more digits in the dividend, we add a zero to the remainder making it 550, and continue the process.

On to step 9:
395 can be fit into 550 1 times, resulting in a remainder of 155.
The next digit of our result is 1. 
Result so far: 129648.1
If we subtract 395 from 550, we get 155.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1550, and continue the process.

Moving on to step 10:
If we divide 1550 by 395, we get 3 and a remainder of 365.
Use 3 as the next digit of our solution. 
Result so far: 129648.13
If we subtract 1185 from 1550, we get 365.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3650, and continue the process.

Going ahead to step 11:
When dividing 3650 by 395, we get 9 with a remainder of 95.
Write down 9 as next digit of the result. 
Result so far: 129648.139
If we subtract 3555 from 3650, we get 95.
Since there are no more digits in the dividend, we add a zero to the remainder making it 950, and continue the process.

On to step 12:
The number 395 fits into 950 2 times, leaving a remainder of 160.
Write down 2 as next digit of the result. 
Result so far: 129648.1392
Subtracting 790 from 950 leaves us with 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1600, and continue the process.

Moving on to step 13:
When dividing 1600 by 395, we get 4 with a remainder of 20.
Write down 4 as next digit of the result. 
Result so far: 129648.13924
If we take 1580 away from 1600, we end up with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 14:
395 can be fit into 200 0 times, resulting in a remainder of 200.
Use 0 as the next digit of our solution. 
Result so far: 129648.13924
The remainder is 200 after subtracting 0 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2000, and continue the process.

Advancing to step 15:
395 can be fit into 2000 5 times, resulting in a remainder of 25.
Record the quotient 5 as the next digit in the result. 
Result so far: 129648.1392405
Subtracting 1975 from 2000 leaves us with 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Advancing to step 16:
The number 395 fits into 250 0 times, leaving a remainder of 250.
The number 0 becomes the next digit in our result. 
Result so far: 129648.1392405
Subtracting 0 from 250 leaves us with 250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2500, and continue the process.

The final result is 129648.1392405 with a remainder of 2.5e-07.