We divide 423729 by 21
We want to figure out the number of times 423729 can be divided by 21.

Let's proceed to step 1:
21 can be fit into 4 0 times, resulting in a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Append the next digit (2) from the dividend to 4 and continue with: 42 / 21

Step 2:
When dividing 42 by 21, we get 2 with a remainder of 0.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Deduct 42 from 42 and we're left with 0.
Include the next digit (3) from the dividend after 0, then repeat: 3 / 21

Step 3:
The number 21 fits into 3 0 times, leaving a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 20.0
If we subtract 0 from 3, we get 3.
Fetch the next digit (7) from the dividend, attach it to 3 and continue: 37 / 21

Advancing to step 4:
37 divided by 21 is 1 with a remainder of 16.
Write down 1 as next digit of the result. 
Result so far: 201.0
Subtracting 21 from 37 leaves us with 16.
Grab the next digit (2) from the dividend, add it to 16, then carry on: 162 / 21

Step 5:
When dividing 162 by 21, we get 7 with a remainder of 15.
Put 7 as the next digit of the answer. 
Result so far: 2017.0
The remainder is 15 after subtracting 147 from 162.
Grab the next digit (9) from the dividend, add it to 15, then carry on: 159 / 21

Moving on to step 6:
The number 21 fits into 159 7 times, leaving a remainder of 12.
Record the quotient 7 as the next digit in the result. 
Result so far: 20177.0
Deduct 147 from 159 and we're left with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Let's proceed to step 7:
21 goes into 120 5 times with a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 20177.5
Deduct 105 from 120 and we're left with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 8:
21 goes into 150 7 times with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 20177.57
If we subtract 147 from 150, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

On to step 9:
If we divide 30 by 21, we get 1 and a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 20177.571
If we take 21 away from 30, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 10:
The number 21 fits into 90 4 times, leaving a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 20177.5714
Subtracting 84 from 90 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 11:
21 goes into 60 2 times with a remainder of 18.
The next digit of our result is 2. 
Result so far: 20177.57142
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Going ahead to step 12:
180 divided by 21 is 8 with a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 20177.571428
If we take 168 away from 180, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 13:
The number 21 fits into 120 5 times, leaving a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 20177.5714285
Subtracting 105 from 120 leaves us with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Step 14:
21 goes into 150 7 times with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 20177.57142857
The remainder is 3 after subtracting 147 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Our division results in 20177.57142857 with a remaining 3e-09.