We're dividing 21039 by 81 
We want to divide 21039 by 81.

Advancing to step 1:
When dividing 2 by 81, we get 0 with a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 81

Moving on to step 2:
The number 81 fits into 21 0 times, leaving a remainder of 21.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 21 leaves us with 21.
Bring next digit (0) of the dividend behind the 21 and repeat the process: 210 / 81

On to step 3:
If we divide 210 by 81, we get 2 and a remainder of 48.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Deduct 162 from 210 and we're left with 48.
Take the next digit (3) from the dividend and append it to 48, then repeat: 483 / 81

Moving on to step 4:
483 divided by 81 is 5 with a remainder of 78.
Put 5 as the next digit of the answer. 
Result so far: 25.0
Deduct 405 from 483 and we're left with 78.
Append the next digit (9) from the dividend to 78 and continue with: 789 / 81

Step 5:
81 goes into 789 9 times with a remainder of 60.
Write down 9 as next digit of the result. 
Result so far: 259.0
Subtract 729 from 789 to get 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Advancing to step 6:
81 goes into 600 7 times with a remainder of 33.
Write down 7 as next digit of the result. 
Result so far: 259.7
The remainder is 33 after subtracting 567 from 600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

Advancing to step 7:
330 divided by 81 is 4 with a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 259.74
The remainder is 6 after subtracting 324 from 330.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 8:
When dividing 60 by 81, we get 0 with a remainder of 60.
Put 0 as the next digit of the answer. 
Result so far: 259.74
Deduct 0 from 60 and we're left with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

On to step 9:
If we divide 600 by 81, we get 7 and a remainder of 33.
Record the quotient 7 as the next digit in the result. 
Result so far: 259.7407
Subtract 567 from 600 to get 33.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

Step 10:
When dividing 330 by 81, we get 4 with a remainder of 6.
The next digit of our result is 4. 
Result so far: 259.74074
Deduct 324 from 330 and we're left 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 11:
81 can be fit into 60 0 times, resulting in a remainder of 60.
The next digit of our result is 0. 
Result so far: 259.74074
Deduct 0 from 60 and we're left with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

On to step 12:
The number 81 fits into 600 7 times, leaving a remainder of 33.
The next digit of our result is 7. 
Result so far: 259.7407407
If we subtract 567 from 600, we get 33.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

On to step 13:
81 goes into 330 4 times with a remainder of 6.
The next digit of our result is 4. 
Result so far: 259.74074074
Subtract 324 from 330 to get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The quotient of the division is 259.74074074, and the remainder is 6e-09.