718391 divided by 21 
We want to figure out the number of times 718391 can be divided by 21.

On to step 1:
The number 21 fits into 7 0 times, leaving a remainder of 7.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 7 after subtracting 0 from 7.
Include the next digit (1) from the dividend after 7, then repeat: 71 / 21

Moving on to step 2:
If we divide 71 by 21, we get 3 and a remainder of 8.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Deduct 63 from 71 and we're left with 8.
Fetch the next digit (8) from the dividend, attach it to 8 and continue: 88 / 21

Moving on to step 3:
88 divided by 21 is 4 with a remainder of 4.
Put 4 as the next digit of the answer. 
Result so far: 34.0
If we take 84 away from 88, we end up with 4.
Append the next digit (3) from the dividend to 4 and continue with: 43 / 21

On to step 4:
If we divide 43 by 21, we get 2 and a remainder of 1.
Write down 2 as next digit of the result. 
Result so far: 342.0
Deduct 42 from 43 and we're left with 1.
Bring next digit (9) of the dividend behind the 1 and repeat the process: 19 / 21

Going ahead to step 5:
The number 21 fits into 19 0 times, leaving a remainder of 19.
Put 0 as the next digit of the answer. 
Result so far: 3420.0
If we take 0 away from 19, we end up with 19.
Grab the next digit (1) from the dividend, add it to 19, then carry on: 191 / 21

Going ahead to step 6:
The number 21 fits into 191 9 times, leaving a remainder of 2.
Record the quotient 9 as the next digit in the result. 
Result so far: 34209.0
If we take 189 away from 191, 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.

On to step 7:
20 divided by 21 is 0 with a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 34209.0
Subtracting 0 from 20 leaves us 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.

Advancing to step 8:
When dividing 200 by 21, we get 9 with a remainder of 11.
The next digit of our result is 9. 
Result so far: 34209.09
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.

Step 9:
21 goes into 110 5 times with a remainder of 5.
The number 5 becomes the next digit in our result. 
Result so far: 34209.095
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.

Going ahead to step 10:
If we divide 50 by 21, we get 2 and a remainder of 8.
The next digit of our result is 2. 
Result so far: 34209.0952
If we take 42 away from 50, we end up 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.

Let's proceed to step 11:
If we divide 80 by 21, we get 3 and a remainder of 17.
The next digit of our result is 3. 
Result so far: 34209.09523
Deduct 63 from 80 and we're left with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Moving on to step 12:
If we divide 170 by 21, we get 8 and a remainder of 2.
The next digit of our result is 8. 
Result so far: 34209.095238
Deduct 168 from 170 and we're left 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.

Advancing to step 13:
21 goes into 20 0 times with a remainder of 20.
The next digit of our result is 0. 
Result so far: 34209.095238
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.

Moving on to step 14:
200 divided by 21 is 9 with a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 34209.09523809
Deduct 189 from 200 and we're left 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.

The final result is 34209.09523809 with a remainder of 1.1e-08.