We look at the division of 640950 by 21 
Let's see how many times 21 fits into 640950.

Moving on to step 1:
21 goes into 6 0 times with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Take the next digit (4) from the dividend and append it to 6, then repeat: 64 / 21

Going ahead to step 2:
When dividing 64 by 21, we get 3 with a remainder of 1.
The next digit of our result is 3. 
Result so far: 3.0
The remainder is 1 after subtracting 63 from 64.
Take the next digit (0) from the dividend and append it to 1, then repeat: 10 / 21

Let's proceed to step 3:
21 can be fit into 10 0 times, resulting in a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 30.0
If we take 0 away from 10, we end up with 10.
Grab the next digit (9) from the dividend, add it to 10, then carry on: 109 / 21

Going ahead to step 4:
109 divided by 21 is 5 with a remainder of 4.
Put 5 as the next digit of the answer. 
Result so far: 305.0
If we subtract 105 from 109, we get 4.
Grab the next digit (5) from the dividend, add it to 4, then carry on: 45 / 21

Going ahead to step 5:
If we divide 45 by 21, we get 2 and a remainder of 3.
Put 2 as the next digit of the answer. 
Result so far: 3052.0
If we take 42 away from 45, we end up with 3.
Fetch the next digit (0) from the dividend, attach it to 3 and continue: 30 / 21

Step 6:
21 can be fit into 30 1 times, resulting in a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 30521.0
Subtracting 21 from 30 leaves us 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.

Moving on to step 7:
If we divide 90 by 21, we get 4 and a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 30521.4
If we subtract 84 from 90, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Advancing to step 8:
If we divide 60 by 21, we get 2 and a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 30521.42
Deduct 42 from 60 and we're left 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.

Step 9:
When dividing 180 by 21, we get 8 with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 30521.428
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Advancing to step 10:
21 can be fit into 120 5 times, resulting in a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 30521.4285
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 11:
150 divided by 21 is 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 30521.42857
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.

Advancing to step 12:
When dividing 30 by 21, we get 1 with a remainder of 9.
The next digit of our result is 1. 
Result so far: 30521.428571
Subtracting 21 from 30 leaves us 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.

Let's proceed to step 13:
When dividing 90 by 21, we get 4 with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 30521.4285714
Deduct 84 from 90 and we're left 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.

Moving on to step 14:
If we divide 60 by 21, we get 2 and a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 30521.42857142
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.

After the division, we end up with 30521.42857142 and a remainder of 1.8e-08.