51315394 ÷ 400 
We want to divide 51315394 by 400.

Let's proceed to step 1:
When dividing 5 by 400, we get 0 with a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 5, we get 5.
Include the next digit (1) from the dividend after 5, then repeat: 51 / 400

Advancing to step 2:
If we divide 51 by 400, we get 0 and a remainder of 51.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 51 leaves us with 51.
Bring next digit (3) of the dividend behind the 51 and repeat the process: 513 / 400

Step 3:
When dividing 513 by 400, we get 1 with a remainder of 113.
Use 1 as the next digit of our solution. 
Result so far: 1.0
If we take 400 away from 513, we end up with 113.
Grab the next digit (1) from the dividend, add it to 113, then carry on: 1131 / 400

On to step 4:
400 can be fit into 1131 2 times, resulting in a remainder of 331.
Write down 2 as next digit of the result. 
Result so far: 12.0
The remainder is 331 after subtracting 800 from 1131.
Grab the next digit (5) from the dividend, add it to 331, then carry on: 3315 / 400

Let's proceed to step 5:
The number 400 fits into 3315 8 times, leaving a remainder of 115.
Record the quotient 8 as the next digit in the result. 
Result so far: 128.0
If we subtract 3200 from 3315, we get 115.
Append the next digit (3) from the dividend to 115 and continue with: 1153 / 400

Let's proceed to step 6:
If we divide 1153 by 400, we get 2 and a remainder of 353.
Use 2 as the next digit of our solution. 
Result so far: 1282.0
The remainder is 353 after subtracting 800 from 1153.
Include the next digit (9) from the dividend after 353, then repeat: 3539 / 400

Advancing to step 7:
400 can be fit into 3539 8 times, resulting in a remainder of 339.
Use 8 as the next digit of our solution. 
Result so far: 12828.0
If we subtract 3200 from 3539, we get 339.
Bring next digit (4) of the dividend behind the 339 and repeat the process: 3394 / 400

Going ahead to step 8:
400 goes into 3394 8 times with a remainder of 194.
Write down 8 as next digit of the result. 
Result so far: 128288.0
If we take 3200 away from 3394, we end up with 194.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1940, and continue the process.

Going ahead to step 9:
400 goes into 1940 4 times with a remainder of 340.
Write down 4 as next digit of the result. 
Result so far: 128288.4
If we take 1600 away from 1940, we end up with 340.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3400, and continue the process.

On to step 10:
When dividing 3400 by 400, we get 8 with a remainder of 200.
Write down 8 as next digit of the result. 
Result so far: 128288.48
The remainder is 200 after subtracting 3200 from 3400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2000, and continue the process.

Going ahead to step 11:
400 goes into 2000 5 times with a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 128288.485
The remainder is 0 after subtracting 2000 from 2000.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 12:
400 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 128288.485
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 13:
When dividing 0 by 400, we get 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 128288.485
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

In conclusion, the division gives 128288.485 with a balance of 0.0.