We divide 644166 by 21
We want to figure out the number of times 644166 can be divided by 21.

Step 1:
The number 21 fits into 6 0 times, leaving a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 21

Moving on to step 2:
64 divided by 21 is 3 with a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 3.0
Subtracting 63 from 64 leaves us with 1.
Fetch the next digit (4) from the dividend, attach it to 1 and continue: 14 / 21

Let's proceed to step 3:
The number 21 fits into 14 0 times, leaving a remainder of 14.
The number 0 becomes the next digit in our result. 
Result so far: 30.0
Deduct 0 from 14 and we're left with 14.
Include the next digit (1) from the dividend after 14, then repeat: 141 / 21

Moving on to step 4:
21 goes into 141 6 times with a remainder of 15.
Write down 6 as next digit of the result. 
Result so far: 306.0
The remainder is 15 after subtracting 126 from 141.
Include the next digit (6) from the dividend after 15, then repeat: 156 / 21

On to step 5:
The number 21 fits into 156 7 times, leaving a remainder of 9.
Put 7 as the next digit of the answer. 
Result so far: 3067.0
Deduct 147 from 156 and we're left with 9.
Grab the next digit (6) from the dividend, add it to 9, then carry on: 96 / 21

Let's proceed to step 6:
96 divided by 21 is 4 with a remainder of 12.
Record the quotient 4 as the next digit in the result. 
Result so far: 30674.0
If we subtract 84 from 96, we get 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: 30674.5
The remainder is 15 after subtracting 105 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Step 8:
When dividing 150 by 21, we get 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 30674.57
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.

Let's proceed to step 9:
21 goes into 30 1 times with a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 30674.571
If we subtract 21 from 30, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 10:
21 goes into 90 4 times with a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 30674.5714
If we take 84 away from 90, we end up 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.

Going ahead to step 11:
21 can be fit into 60 2 times, resulting in a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 30674.57142
If we take 42 away from 60, we end up with 18.
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:
If we divide 180 by 21, we get 8 and a remainder of 12.
The next digit of our result is 8. 
Result so far: 30674.571428
If we subtract 168 from 180, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Going ahead to step 13:
120 divided by 21 is 5 with a remainder of 15.
Use 5 as the next digit of our solution. 
Result so far: 30674.5714285
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.
Use 7 as the next digit of our solution. 
Result so far: 30674.57142857
Deduct 147 from 150 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

After the division, we end up with 30674.57142857 and a remainder of 3e-09.