420248 ÷ 20 
We want to figure out the number of times 420248 can be divided by 20.

On to step 1:
If we divide 4 by 20, we get 0 and 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.
Include the next digit (2) from the dividend after 4, then repeat: 42 / 20

Advancing to step 2:
When dividing 42 by 20, we get 2 with a remainder of 2.
The next digit of our result is 2. 
Result so far: 2.0
Subtract 40 from 42 to get 2.
Bring next digit (0) of the dividend behind the 2 and repeat the process: 20 / 20

Going ahead to step 3:
20 divided by 20 is 1 with a remainder of 0.
Use 1 as the next digit of our solution. 
Result so far: 21.0
The remainder is 0 after subtracting 20 from 20.
Bring next digit (2) of the dividend behind the 0 and repeat the process: 2 / 20

Step 4:
20 goes into 2 0 times with a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 210.0
If we take 0 away from 2, we end up with 2.
Append the next digit (4) from the dividend to 2 and continue with: 24 / 20

Going ahead to step 5:
20 can be fit into 24 1 times, resulting in a remainder of 4.
Record the quotient 1 as the next digit in the result. 
Result so far: 2101.0
Subtract 20 from 24 to get 4.
Take the next digit (8) from the dividend and append it to 4, then repeat: 48 / 20

Advancing to step 6:
48 divided by 20 is 2 with a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 21012.0
Subtract 40 from 48 to get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Going ahead to step 7:
The number 20 fits into 80 4 times, leaving a remainder of 0.
Put 4 as the next digit of the answer. 
Result so far: 21012.4
If we take 80 away from 80, 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.

On to step 8:
The number 20 fits into 0 0 times, leaving a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 21012.4
If we subtract 0 from 0, 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.

Let's proceed to step 9:
If we divide 0 by 20, we get 0 and a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 21012.4
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.

The final result is 21012.4 with a remainder of 0.0.