We divide 421243 by 21
Our goal is to divide 421243 by 21.

Moving on to step 1:
When dividing 4 by 21, we get 0 with a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 4 and we're left with 4.
Append the next digit (2) from the dividend to 4 and continue with: 42 / 21

Moving on to step 2:
42 divided by 21 is 2 with a remainder of 0.
The next digit of our result is 2. 
Result so far: 2.0
Subtracting 42 from 42 leaves us with 0.
Fetch the next digit (1) from the dividend, attach it to 0 and continue: 1 / 21

On to step 3:
21 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 20.0
Subtract 0 from 1 to get 1.
Append the next digit (2) from the dividend to 1 and continue with: 12 / 21

Advancing to step 4:
12 divided by 21 is 0 with a remainder of 12.
The next digit of our result is 0. 
Result so far: 200.0
The remainder is 12 after subtracting 0 from 12.
Grab the next digit (4) from the dividend, add it to 12, then carry on: 124 / 21

Step 5:
The number 21 fits into 124 5 times, leaving a remainder of 19.
Put 5 as the next digit of the answer. 
Result so far: 2005.0
The remainder is 19 after subtracting 105 from 124.
Append the next digit (3) from the dividend to 19 and continue with: 193 / 21

Moving on to step 6:
If we divide 193 by 21, we get 9 and a remainder of 4.
Use 9 as the next digit of our solution. 
Result so far: 20059.0
Deduct 189 from 193 and we're left 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.

Let's proceed to step 7:
The number 21 fits into 40 1 times, leaving a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 20059.1
If we take 21 away from 40, we end up 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 8:
When dividing 190 by 21, we get 9 with a remainder of 1.
The next digit of our result is 9. 
Result so far: 20059.19
Subtract 189 from 190 to 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.

Step 9:
10 divided by 21 is 0 with a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 20059.19
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.

Advancing to step 10:
The number 21 fits into 100 4 times, leaving a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 20059.1904
If we subtract 84 from 100, we get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Step 11:
160 divided by 21 is 7 with a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 20059.19047
The remainder is 13 after subtracting 147 from 160.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

On to step 12:
If we divide 130 by 21, we get 6 and a remainder of 4.
Write down 6 as next digit of the result. 
Result so far: 20059.190476
If we subtract 126 from 130, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 13:
The number 21 fits into 40 1 times, leaving a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 20059.1904761
The remainder is 19 after subtracting 21 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 14:
21 can be fit into 190 9 times, resulting in a remainder of 1.
The number 9 becomes the next digit in our result. 
Result so far: 20059.19047619
Subtract 189 from 190 to 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.

The quotient of the division is 20059.19047619, and the remainder is 1e-09.