644096 divided by 21 
We want to figure out the number of times 644096 can be divided by 21.

Advancing to step 1:
If we divide 6 by 21, we get 0 and a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Fetch the next digit (4) from the dividend, attach it to 6 and continue: 64 / 21

Advancing to step 2:
When dividing 64 by 21, we get 3 with a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
Subtracting 63 from 64 leaves us with 1.
Grab the next digit (4) from the dividend, add it to 1, then carry on: 14 / 21

Step 3:
21 goes into 14 0 times with a remainder of 14.
Record the quotient 0 as the next digit in the result. 
Result so far: 30.0
Deduct 0 from 14 and we're left with 14.
Grab the next digit (0) from the dividend, add it to 14, then carry on: 140 / 21

Advancing to step 4:
21 goes into 140 6 times with a remainder of 14.
Put 6 as the next digit of the answer. 
Result so far: 306.0
Subtracting 126 from 140 leaves us with 14.
Include the next digit (9) from the dividend after 14, then repeat: 149 / 21

Step 5:
149 divided by 21 is 7 with a remainder of 2.
The next digit of our result is 7. 
Result so far: 3067.0
Subtracting 147 from 149 leaves us with 2.
Grab the next digit (6) from the dividend, add it to 2, then carry on: 26 / 21

Moving on to step 6:
When dividing 26 by 21, we get 1 with a remainder of 5.
Put 1 as the next digit of the answer. 
Result so far: 30671.0
Subtracting 21 from 26 leaves us with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Advancing to step 7:
21 can be fit into 50 2 times, resulting in a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 30671.2
Subtract 42 from 50 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.

Moving on to step 8:
21 can be fit into 80 3 times, resulting in a remainder of 17.
The number 3 becomes the next digit in our result. 
Result so far: 30671.23
Subtract 63 from 80 to get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Step 9:
If we divide 170 by 21, we get 8 and a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 30671.238
If we take 168 away from 170, we end up 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.

Step 10:
If we divide 20 by 21, we get 0 and a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 30671.238
Deduct 0 from 20 and we're left with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 11:
21 can be fit into 200 9 times, resulting in a remainder of 11.
Write down 9 as next digit of the result. 
Result so far: 30671.23809
If we take 189 away from 200, we end up with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 12:
The number 21 fits into 110 5 times, leaving a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 30671.238095
Deduct 105 from 110 and we're left with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Let's proceed to step 13:
21 goes into 50 2 times with a remainder of 8.
Write down 2 as next digit of the result. 
Result so far: 30671.2380952
Subtracting 42 from 50 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 14:
21 can be fit into 80 3 times, resulting in a remainder of 17.
Put 3 as the next digit of the answer. 
Result so far: 30671.23809523
If we subtract 63 from 80, we get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

After the division, we end up with 30671.23809523 and a remainder of 1.7e-08.