721664 divided by 21 
Let's see how many times 21 fits into 721664.

Moving on to step 1:
If we divide 7 by 21, we get 0 and a remainder of 7.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 7 and we're left with 7.
Append the next digit (2) from the dividend to 7 and continue with: 72 / 21

Step 2:
72 divided by 21 is 3 with a remainder of 9.
Put 3 as the next digit of the answer. 
Result so far: 3.0
If we take 63 away from 72, we end up with 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 21

Let's proceed to step 3:
91 divided by 21 is 4 with a remainder of 7.
The next digit of our result is 4. 
Result so far: 34.0
Deduct 84 from 91 and we're left with 7.
Take the next digit (6) from the dividend and append it to 7, then repeat: 76 / 21

Step 4:
The number 21 fits into 76 3 times, leaving a remainder of 13.
Use 3 as the next digit of our solution. 
Result so far: 343.0
Deduct 63 from 76 and we're left with 13.
Include the next digit (6) from the dividend after 13, then repeat: 136 / 21

Advancing to step 5:
136 divided by 21 is 6 with a remainder of 10.
Write down 6 as next digit of the result. 
Result so far: 3436.0
Subtract 126 from 136 to get 10.
Take the next digit (4) from the dividend and append it to 10, then repeat: 104 / 21

Advancing to step 6:
21 goes into 104 4 times with a remainder of 20.
Put 4 as the next digit of the answer. 
Result so far: 34364.0
The remainder is 20 after subtracting 84 from 104.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 7:
If we divide 200 by 21, we get 9 and a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 34364.9
The remainder is 11 after subtracting 189 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Let's proceed to step 8:
21 can be fit into 110 5 times, resulting in a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 34364.95
Subtract 105 from 110 to get 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 9:
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: 34364.952
Subtracting 42 from 50 leaves us 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.

On to step 10:
21 goes into 80 3 times with a remainder of 17.
Use 3 as the next digit of our solution. 
Result so far: 34364.9523
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.

On to step 11:
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: 34364.95238
The remainder is 2 after subtracting 168 from 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Going ahead to step 12:
The number 21 fits into 20 0 times, leaving a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 34364.95238
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.

Step 13:
21 can be fit into 200 9 times, resulting in a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 34364.9523809
If we subtract 189 from 200, we get 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 14:
When dividing 110 by 21, we get 5 with a remainder of 5.
Put 5 as the next digit of the answer. 
Result so far: 34364.95238095
If we take 105 away from 110, we end up 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.

The quotient of the division is 34364.95238095, and the remainder is 5e-09.