We're dividing 81399 by 51 
We're looking to find how many times 51 goes into 81399.

Let's proceed to step 1:
8 divided by 51 is 0 with a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Include the next digit (1) from the dividend after 8, then repeat: 81 / 51

Going ahead to step 2:
81 divided by 51 is 1 with a remainder of 30.
The next digit of our result is 1. 
Result so far: 1.0
If we take 51 away from 81, we end up with 30.
Append the next digit (3) from the dividend to 30 and continue with: 303 / 51

Going ahead to step 3:
51 goes into 303 5 times with a remainder of 48.
Put 5 as the next digit of the answer. 
Result so far: 15.0
Subtract 255 from 303 to get 48.
Bring next digit (9) of the dividend behind the 48 and repeat the process: 489 / 51

Step 4:
51 can be fit into 489 9 times, resulting in a remainder of 30.
Record the quotient 9 as the next digit in the result. 
Result so far: 159.0
Subtract 459 from 489 to get 30.
Take the next digit (9) from the dividend and append it to 30, then repeat: 309 / 51

Advancing to step 5:
When dividing 309 by 51, we get 6 with a remainder of 3.
The number 6 becomes the next digit in our result. 
Result so far: 1596.0
Subtract 306 from 309 to get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Step 6:
30 divided by 51 is 0 with a remainder of 30.
Record the quotient 0 as the next digit in the result. 
Result so far: 1596.0
Subtracting 0 from 30 leaves us with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Advancing to step 7:
51 can be fit into 300 5 times, resulting in a remainder of 45.
Record the quotient 5 as the next digit in the result. 
Result so far: 1596.05
Subtracting 255 from 300 leaves us with 45.
Since there are no more digits in the dividend, we add a zero to the remainder making it 450, and continue the process.

Step 8:
450 divided by 51 is 8 with a remainder of 42.
Record the quotient 8 as the next digit in the result. 
Result so far: 1596.058
Subtract 408 from 450 to get 42.
Since there are no more digits in the dividend, we add a zero to the remainder making it 420, and continue the process.

Moving on to step 9:
420 divided by 51 is 8 with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 1596.0588
If we take 408 away from 420, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

After the division, we end up with 1596.0588 and a remainder of 0.00012.