Let's divide 123837 by 21
We want to divide 123837 by 21.

Advancing to step 1:
21 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 1 and we're left with 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 21

Step 2:
21 goes into 12 0 times with a remainder of 12.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 12, we end up with 12.
Bring next digit (3) of the dividend behind the 12 and repeat the process: 123 / 21

Going ahead to step 3:
21 can be fit into 123 5 times, resulting in a remainder of 18.
Write down 5 as next digit of the result. 
Result so far: 5.0
The remainder is 18 after subtracting 105 from 123.
Grab the next digit (8) from the dividend, add it to 18, then carry on: 188 / 21

Let's proceed to step 4:
If we divide 188 by 21, we get 8 and a remainder of 20.
Put 8 as the next digit of the answer. 
Result so far: 58.0
Subtract 168 from 188 to get 20.
Append the next digit (3) from the dividend to 20 and continue with: 203 / 21

Step 5:
When dividing 203 by 21, we get 9 with a remainder of 14.
Use 9 as the next digit of our solution. 
Result so far: 589.0
If we take 189 away from 203, we end up with 14.
Fetch the next digit (7) from the dividend, attach it to 14 and continue: 147 / 21

Let's proceed to step 6:
When dividing 147 by 21, we get 7 with a remainder of 0.
The number 7 becomes the next digit in our result. 
Result so far: 5897.0
If we take 147 away from 147, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 7:
If we divide 0 by 21, we get 0 and a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 5897.0
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 8:
If we divide 0 by 21, we get 0 and a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 5897.0
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final outcome is 5897.0, with a leftover of 0.0.