We're dividing 423902 by 20 
Let's see how many times 20 fits into 423902.

Let's proceed to step 1:
The number 20 fits into 4 0 times, leaving a remainder of 4.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 4 after subtracting 0 from 4.
Take the next digit (2) from the dividend and append it to 4, then repeat: 42 / 20

Going ahead to step 2:
When dividing 42 by 20, we get 2 with a remainder of 2.
Use 2 as the next digit of our solution. 
Result so far: 2.0
If we take 40 away from 42, we end up with 2.
Bring next digit (3) of the dividend behind the 2 and repeat the process: 23 / 20

Going ahead to step 3:
23 divided by 20 is 1 with a remainder of 3.
Put 1 as the next digit of the answer. 
Result so far: 21.0
If we take 20 away from 23, we end up with 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 20

Moving on to step 4:
20 goes into 39 1 times with a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 211.0
Subtract 20 from 39 to get 19.
Append the next digit (0) from the dividend to 19 and continue with: 190 / 20

Going ahead to step 5:
20 goes into 190 9 times with a remainder of 10.
Write down 9 as next digit of the result. 
Result so far: 2119.0
If we take 180 away from 190, we end up with 10.
Append the next digit (2) from the dividend to 10 and continue with: 102 / 20

Advancing to step 6:
When dividing 102 by 20, we get 5 with a remainder of 2.
Write down 5 as next digit of the result. 
Result so far: 21195.0
Subtracting 100 from 102 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 7:
20 goes into 20 1 times with a remainder of 0.
Put 1 as the next digit of the answer. 
Result so far: 21195.1
If we subtract 20 from 20, 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.

Moving on to step 8:
The number 20 fits into 0 0 times, leaving a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 21195.1
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.

On to step 9:
If we divide 0 by 20, we get 0 and a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 21195.1
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Our division results in 21195.1 with a remaining 0.0.