636720 divided by 21 
We're looking to find how many times 21 goes into 636720.

Step 1:
21 goes into 6 0 times with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Append the next digit (3) from the dividend to 6 and continue with: 63 / 21

Advancing to step 2:
If we divide 63 by 21, we get 3 and a remainder of 0.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
The remainder is 0 after subtracting 63 from 63.
Take the next digit (6) from the dividend and append it to 0, then repeat: 6 / 21

On to step 3:
If we divide 6 by 21, we get 0 and a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 30.0
Subtracting 0 from 6 leaves us with 6.
Append the next digit (7) from the dividend to 6 and continue with: 67 / 21

Let's proceed to step 4:
If we divide 67 by 21, we get 3 and a remainder of 4.
Write down 3 as next digit of the result. 
Result so far: 303.0
If we take 63 away from 67, we end up with 4.
Grab the next digit (2) from the dividend, add it to 4, then carry on: 42 / 21

Step 5:
21 can be fit into 42 2 times, resulting in a remainder of 0.
The number 2 becomes the next digit in our result. 
Result so far: 3032.0
If we subtract 42 from 42, we get 0.
Grab the next digit (0) from the dividend, add it to 0, then carry on: 0 / 21

On to step 6:
The number 21 fits into 0 0 times, leaving a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 30320.0
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Let's proceed to step 7:
0 divided by 21 is 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 30320.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

On to step 8:
21 goes into 0 0 times with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 30320.0
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The quotient of the division is 30320.0, and the remainder is 0.0.