Let's divide 139102 by 21
We want to divide 139102 by 21.

On to step 1:
21 goes into 1 0 times with a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Bring next digit (3) of the dividend behind the 1 and repeat the process: 13 / 21

On to step 2:
The number 21 fits into 13 0 times, leaving a remainder of 13.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 13, we end up with 13.
Bring next digit (9) of the dividend behind the 13 and repeat the process: 139 / 21

Going ahead to step 3:
The number 21 fits into 139 6 times, leaving a remainder of 13.
Record the quotient 6 as the next digit in the result. 
Result so far: 6.0
The remainder is 13 after subtracting 126 from 139.
Grab the next digit (1) from the dividend, add it to 13, then carry on: 131 / 21

On to step 4:
The number 21 fits into 131 6 times, leaving a remainder of 5.
Write down 6 as next digit of the result. 
Result so far: 66.0
If we take 126 away from 131, we end up with 5.
Append the next digit (0) from the dividend to 5 and continue with: 50 / 21

Step 5:
If we divide 50 by 21, we get 2 and a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 662.0
If we subtract 42 from 50, we get 8.
Take the next digit (2) from the dividend and append it to 8, then repeat: 82 / 21

On to step 6:
The number 21 fits into 82 3 times, leaving a remainder of 19.
The number 3 becomes the next digit in our result. 
Result so far: 6623.0
Subtracting 63 from 82 leaves us with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Going ahead to step 7:
When dividing 190 by 21, we get 9 with a remainder of 1.
Put 9 as the next digit of the answer. 
Result so far: 6623.9
If we subtract 189 from 190, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Advancing to step 8:
21 can be fit into 10 0 times, resulting in a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 6623.9
Deduct 0 from 10 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 9:
The number 21 fits into 100 4 times, leaving a remainder of 16.
Record the quotient 4 as the next digit in the result. 
Result so far: 6623.904
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Let's proceed to step 10:
21 goes into 160 7 times with a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 6623.9047
Subtracting 147 from 160 leaves us with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Moving on to step 11:
If we divide 130 by 21, we get 6 and a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 6623.90476
Subtracting 126 from 130 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 12:
If we divide 40 by 21, we get 1 and a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 6623.904761
If we subtract 21 from 40, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

On to step 13:
21 goes into 190 9 times with a remainder of 1.
The next digit of our result is 9. 
Result so far: 6623.9047619
If we take 189 away from 190, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Advancing to step 14:
The number 21 fits into 10 0 times, leaving a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 6623.9047619
If we take 0 away from 10, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The final outcome is 6623.9047619, with a leftover of 1e-08.