We look at the division of 51493225 by 399 
We want to figure out the number of times 51493225 can be divided by 399.

Advancing to step 1:
If we divide 5 by 399, we get 0 and a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Append the next digit (1) from the dividend to 5 and continue with: 51 / 399

Going ahead to step 2:
399 can be fit into 51 0 times, resulting in a remainder of 51.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 51 and we're left with 51.
Include the next digit (4) from the dividend after 51, then repeat: 514 / 399

Moving on to step 3:
If we divide 514 by 399, we get 1 and a remainder of 115.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Deduct 399 from 514 and we're left with 115.
Grab the next digit (9) from the dividend, add it to 115, then carry on: 1159 / 399

Moving on to step 4:
The number 399 fits into 1159 2 times, leaving a remainder of 361.
The number 2 becomes the next digit in our result. 
Result so far: 12.0
Subtract 798 from 1159 to get 361.
Append the next digit (3) from the dividend to 361 and continue with: 3613 / 399

Going ahead to step 5:
399 goes into 3613 9 times with a remainder of 22.
The next digit of our result is 9. 
Result so far: 129.0
Subtract 3591 from 3613 to get 22.
Take the next digit (2) from the dividend and append it to 22, then repeat: 222 / 399

On to step 6:
399 can be fit into 222 0 times, resulting in a remainder of 222.
Write down 0 as next digit of the result. 
Result so far: 1290.0
The remainder is 222 after subtracting 0 from 222.
Take the next digit (2) from the dividend and append it to 222, then repeat: 2222 / 399

Going ahead to step 7:
If we divide 2222 by 399, we get 5 and a remainder of 227.
The next digit of our result is 5. 
Result so far: 12905.0
Deduct 1995 from 2222 and we're left with 227.
Bring next digit (5) of the dividend behind the 227 and repeat the process: 2275 / 399

Going ahead to step 8:
399 goes into 2275 5 times with a remainder of 280.
The next digit of our result is 5. 
Result so far: 129055.0
The remainder is 280 after subtracting 1995 from 2275.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2800, and continue the process.

Going ahead to step 9:
2800 divided by 399 is 7 with a remainder of 7.
The number 7 becomes the next digit in our result. 
Result so far: 129055.7
Subtracting 2793 from 2800 leaves us with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Advancing to step 10:
399 can be fit into 70 0 times, resulting in a remainder of 70.
Write down 0 as next digit of the result. 
Result so far: 129055.7
Subtract 0 from 70 to get 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Going ahead to step 11:
700 divided by 399 is 1 with a remainder of 301.
Write down 1 as next digit of the result. 
Result so far: 129055.701
If we subtract 399 from 700, we get 301.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3010, and continue the process.

Moving on to step 12:
When dividing 3010 by 399, we get 7 with a remainder of 217.
Put 7 as the next digit of the answer. 
Result so far: 129055.7017
If we take 2793 away from 3010, we end up with 217.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2170, and continue the process.

On to step 13:
399 can be fit into 2170 5 times, resulting in a remainder of 175.
Use 5 as the next digit of our solution. 
Result so far: 129055.70175
If we take 1995 away from 2170, we end up with 175.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1750, and continue the process.

Let's proceed to step 14:
When dividing 1750 by 399, we get 4 with a remainder of 154.
The number 4 becomes the next digit in our result. 
Result so far: 129055.701754
Subtract 1596 from 1750 to get 154.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1540, and continue the process.

Going ahead to step 15:
399 goes into 1540 3 times with a remainder of 343.
The next digit of our result is 3. 
Result so far: 129055.7017543
If we take 1197 away from 1540, we end up with 343.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3430, and continue the process.

Advancing to step 16:
If we divide 3430 by 399, we get 8 and a remainder of 238.
The next digit of our result is 8. 
Result so far: 129055.70175438
If we take 3192 away from 3430, we end up with 238.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2380, and continue the process.

After the division, we end up with 129055.70175438 and a remainder of 2.38e-07.