We're dividing 421237 by 2 
We want to divide 421237 by 2.

Step 1:
When dividing 4 by 2, we get 2 with a remainder of 0.
Write down 2 as next digit of the result. 
Result so far: 2.0
Deduct 4 from 4 and we're left with 0.
Take the next digit (2) from the dividend and append it to 0, then repeat: 2 / 2

Going ahead to step 2:
If we divide 2 by 2, we get 1 and a remainder of 0.
The number 1 becomes the next digit in our result. 
Result so far: 21.0
Deduct 2 from 2 and we're left with 0.
Take the next digit (1) from the dividend and append it to 0, then repeat: 1 / 2

Going ahead to step 3:
When dividing 1 by 2, we get 0 with a remainder of 1.
The next digit of our result is 0. 
Result so far: 210.0
The remainder is 1 after subtracting 0 from 1.
Grab the next digit (2) from the dividend, add it to 1, then carry on: 12 / 2

Advancing to step 4:
The number 2 fits into 12 6 times, leaving a remainder of 0.
Write down 6 as next digit of the result. 
Result so far: 2106.0
The remainder is 0 after subtracting 12 from 12.
Include the next digit (3) from the dividend after 0, then repeat: 3 / 2

Let's proceed to step 5:
If we divide 3 by 2, we get 1 and a remainder of 1.
Record the quotient 1 as the next digit in the result. 
Result so far: 21061.0
The remainder is 1 after subtracting 2 from 3.
Bring next digit (7) of the dividend behind the 1 and repeat the process: 17 / 2

Step 6:
2 goes into 17 8 times with a remainder of 1.
Record the quotient 8 as the next digit in the result. 
Result so far: 210618.0
If we subtract 16 from 17, 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.

On to step 7:
The number 2 fits into 10 5 times, leaving a remainder of 0.
Use 5 as the next digit of our solution. 
Result so far: 210618.5
If we subtract 10 from 10, we 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.

Step 8:
2 goes into 0 0 times with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 210618.5
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.

Let's proceed to step 9:
2 can be fit into 0 0 times, resulting in a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 210618.5
Deduct 0 from 0 and we're left 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.

After the division, we end up with 210618.5 and a remainder of 0.0.