We look at the division of 51391320 by 864 
We're looking to find how many times 864 goes into 51391320.

Moving on to step 1:
The number 864 fits into 5 0 times, leaving a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 5, we end up with 5.
Include the next digit (1) from the dividend after 5, then repeat: 51 / 864

Moving on to step 2:
51 divided by 864 is 0 with a remainder of 51.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 51 after subtracting 0 from 51.
Fetch the next digit (3) from the dividend, attach it to 51 and continue: 513 / 864

Moving on to step 3:
864 can be fit into 513 0 times, resulting in a remainder of 513.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 513 to get 513.
Take the next digit (9) from the dividend and append it to 513, then repeat: 5139 / 864

Let's proceed to step 4:
When dividing 5139 by 864, we get 5 with a remainder of 819.
The number 5 becomes the next digit in our result. 
Result so far: 5.0
Subtract 4320 from 5139 to get 819.
Fetch the next digit (1) from the dividend, attach it to 819 and continue: 8191 / 864

Going ahead to step 5:
8191 divided by 864 is 9 with a remainder of 415.
The number 9 becomes the next digit in our result. 
Result so far: 59.0
Subtracting 7776 from 8191 leaves us with 415.
Append the next digit (3) from the dividend to 415 and continue with: 4153 / 864

Moving on to step 6:
If we divide 4153 by 864, we get 4 and a remainder of 697.
Use 4 as the next digit of our solution. 
Result so far: 594.0
If we subtract 3456 from 4153, we get 697.
Grab the next digit (2) from the dividend, add it to 697, then carry on: 6972 / 864

On to step 7:
The number 864 fits into 6972 8 times, leaving a remainder of 60.
The next digit of our result is 8. 
Result so far: 5948.0
The remainder is 60 after subtracting 6912 from 6972.
Bring next digit (0) of the dividend behind the 60 and repeat the process: 600 / 864

On to step 8:
When dividing 600 by 864, we get 0 with a remainder of 600.
Put 0 as the next digit of the answer. 
Result so far: 59480.0
Subtracting 0 from 600 leaves us with 600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6000, and continue the process.

Moving on to step 9:
864 can be fit into 6000 6 times, resulting in a remainder of 816.
Record the quotient 6 as the next digit in the result. 
Result so far: 59480.6
If we take 5184 away from 6000, we end up with 816.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8160, and continue the process.

Let's proceed to step 10:
864 goes into 8160 9 times with a remainder of 384.
The next digit of our result is 9. 
Result so far: 59480.69
The remainder is 384 after subtracting 7776 from 8160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3840, and continue the process.

Moving on to step 11:
If we divide 3840 by 864, we get 4 and a remainder of 384.
The number 4 becomes the next digit in our result. 
Result so far: 59480.694
If we subtract 3456 from 3840, we get 384.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3840, and continue the process.

Going ahead to step 12:
3840 divided by 864 is 4 with a remainder of 384.
The number 4 becomes the next digit in our result. 
Result so far: 59480.6944
The remainder is 384 after subtracting 3456 from 3840.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3840, and continue the process.

Our division results in 59480.6944 with a remaining 0.00384.