We look at the division of 642920 by 21 
We want to divide 642920 by 21.

Let's proceed to step 1:
If we divide 6 by 21, we get 0 and a remainder of 6.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 21

Going ahead to step 2:
64 divided by 21 is 3 with a remainder of 1.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
Subtract 63 from 64 to get 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 21

Advancing to step 3:
The number 21 fits into 12 0 times, leaving a remainder of 12.
The number 0 becomes the next digit in our result. 
Result so far: 30.0
The remainder is 12 after subtracting 0 from 12.
Include the next digit (9) from the dividend after 12, then repeat: 129 / 21

On to step 4:
21 can be fit into 129 6 times, resulting in a remainder of 3.
Put 6 as the next digit of the answer. 
Result so far: 306.0
If we subtract 126 from 129, we get 3.
Bring next digit (2) of the dividend behind the 3 and repeat the process: 32 / 21

Moving on to step 5:
32 divided by 21 is 1 with a remainder of 11.
Put 1 as the next digit of the answer. 
Result so far: 3061.0
Deduct 21 from 32 and we're left with 11.
Take the next digit (0) from the dividend and append it to 11, then repeat: 110 / 21

Moving on to step 6:
21 can be fit into 110 5 times, resulting in a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 30615.0
The remainder is 5 after subtracting 105 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

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: 30615.2
The remainder is 8 after subtracting 42 from 50.
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 8:
80 divided by 21 is 3 with a remainder of 17.
The next digit of our result is 3. 
Result so far: 30615.23
The remainder is 17 after subtracting 63 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Advancing to step 9:
21 can be fit into 170 8 times, resulting in a remainder of 2.
Record the quotient 8 as the next digit in the result. 
Result so far: 30615.238
If we subtract 168 from 170, we get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 10:
21 can be fit into 20 0 times, resulting in a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 30615.238
Subtract 0 from 20 to get 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:
200 divided by 21 is 9 with a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 30615.23809
Subtracting 189 from 200 leaves us 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.

Going ahead to step 12:
21 goes into 110 5 times with a remainder of 5.
The next digit of our result is 5. 
Result so far: 30615.238095
The remainder is 5 after subtracting 105 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Step 13:
50 divided by 21 is 2 with a remainder of 8.
The next digit of our result is 2. 
Result so far: 30615.2380952
Deduct 42 from 50 and we're left 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.

Moving on to step 14:
If we divide 80 by 21, we get 3 and a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 30615.23809523
The remainder is 17 after subtracting 63 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

The quotient of the division is 30615.23809523, and the remainder is 1.7e-08.