We're dividing 640098 by 51 
We want to divide 640098 by 51.

Going ahead to step 1:
51 can be fit into 6 0 times, resulting in a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 51

Advancing to step 2:
If we divide 64 by 51, we get 1 and a remainder of 13.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtracting 51 from 64 leaves us with 13.
Take the next digit (0) from the dividend and append it to 13, then repeat: 130 / 51

Let's proceed to step 3:
51 can be fit into 130 2 times, resulting in a remainder of 28.
Write down 2 as next digit of the result. 
Result so far: 12.0
If we take 102 away from 130, we end up with 28.
Bring next digit (0) of the dividend behind the 28 and repeat the process: 280 / 51

On to step 4:
51 goes into 280 5 times with a remainder of 25.
Write down 5 as next digit of the result. 
Result so far: 125.0
If we subtract 255 from 280, we get 25.
Grab the next digit (9) from the dividend, add it to 25, then carry on: 259 / 51

On to step 5:
The number 51 fits into 259 5 times, leaving a remainder of 4.
Record the quotient 5 as the next digit in the result. 
Result so far: 1255.0
Subtract 255 from 259 to get 4.
Append the next digit (8) from the dividend to 4 and continue with: 48 / 51

On to step 6:
51 goes into 48 0 times with a remainder of 48.
Put 0 as the next digit of the answer. 
Result so far: 12550.0
The remainder is 48 after subtracting 0 from 48.
Since there are no more digits in the dividend, we add a zero to the remainder making it 480, and continue the process.

Going ahead to step 7:
If we divide 480 by 51, we get 9 and a remainder of 21.
Use 9 as the next digit of our solution. 
Result so far: 12550.9
If we subtract 459 from 480, we get 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

Let's proceed to step 8:
210 divided by 51 is 4 with a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 12550.94
If we take 204 away from 210, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

On to step 9:
51 goes into 60 1 times with a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 12550.941
If we subtract 51 from 60, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Moving on to step 10:
The number 51 fits into 90 1 times, leaving a remainder of 39.
Write down 1 as next digit of the result. 
Result so far: 12550.9411
Deduct 51 from 90 and we're left with 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

Our division results in 12550.9411 with a remaining 0.00039.