We divide 640309 by 21
We want to divide 640309 by 21.

Moving on to step 1:
When dividing 6 by 21, we get 0 with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Grab the next digit (4) from the dividend, add it to 6, then carry on: 64 / 21

Let's proceed to step 2:
When dividing 64 by 21, we get 3 with a remainder of 1.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
Subtract 63 from 64 to get 1.
Fetch the next digit (0) from the dividend, attach it to 1 and continue: 10 / 21

Advancing to step 3:
21 can be fit into 10 0 times, resulting in a remainder of 10.
The next digit of our result is 0. 
Result so far: 30.0
Deduct 0 from 10 and we're left with 10.
Grab the next digit (3) from the dividend, add it to 10, then carry on: 103 / 21

Step 4:
21 can be fit into 103 4 times, resulting in a remainder of 19.
The number 4 becomes the next digit in our result. 
Result so far: 304.0
The remainder is 19 after subtracting 84 from 103.
Bring next digit (0) of the dividend behind the 19 and repeat the process: 190 / 21

Step 5:
When dividing 190 by 21, we get 9 with a remainder of 1.
The number 9 becomes the next digit in our result. 
Result so far: 3049.0
Subtract 189 from 190 to get 1.
Bring next digit (9) of the dividend behind the 1 and repeat the process: 19 / 21

Advancing to step 6:
19 divided by 21 is 0 with a remainder of 19.
Use 0 as the next digit of our solution. 
Result so far: 30490.0
Subtract 0 from 19 to get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Let's proceed to step 7:
When dividing 190 by 21, we get 9 with a remainder of 1.
Write down 9 as next digit of the result. 
Result so far: 30490.9
The remainder is 1 after subtracting 189 from 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Moving on to step 8:
When dividing 10 by 21, we get 0 with a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 30490.9
Subtract 0 from 10 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Going ahead to step 9:
The number 21 fits into 100 4 times, leaving a remainder of 16.
Record the quotient 4 as the next digit in the result. 
Result so far: 30490.904
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Advancing to step 10:
If we divide 160 by 21, we get 7 and a remainder of 13.
Record the quotient 7 as the next digit in the result. 
Result so far: 30490.9047
Subtracting 147 from 160 leaves us with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Going ahead to step 11:
When dividing 130 by 21, we get 6 with a remainder of 4.
The number 6 becomes the next digit in our result. 
Result so far: 30490.90476
Subtract 126 from 130 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 12:
21 goes into 40 1 times with a remainder of 19.
Put 1 as the next digit of the answer. 
Result so far: 30490.904761
Subtract 21 from 40 to get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Going ahead to step 13:
The number 21 fits into 190 9 times, leaving a remainder of 1.
The number 9 becomes the next digit in our result. 
Result so far: 30490.9047619
If we subtract 189 from 190, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Let's proceed to step 14:
When dividing 10 by 21, we get 0 with a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 30490.9047619
Deduct 0 from 10 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The quotient of the division is 30490.9047619, and the remainder is 1e-08.