We're dividing 663040 by 21 
We're looking to find how many times 21 goes into 663040.

Let's proceed to step 1:
6 divided by 21 is 0 with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 21

On to step 2:
The number 21 fits into 66 3 times, leaving a remainder of 3.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Subtract 63 from 66 to get 3.
Include the next digit (3) from the dividend after 3, then repeat: 33 / 21

On to step 3:
When dividing 33 by 21, we get 1 with a remainder of 12.
Use 1 as the next digit of our solution. 
Result so far: 31.0
If we subtract 21 from 33, we get 12.
Fetch the next digit (0) from the dividend, attach it to 12 and continue: 120 / 21

On to step 4:
When dividing 120 by 21, we get 5 with a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 315.0
Deduct 105 from 120 and we're left with 15.
Grab the next digit (4) from the dividend, add it to 15, then carry on: 154 / 21

Step 5:
21 goes into 154 7 times with a remainder of 7.
Record the quotient 7 as the next digit in the result. 
Result so far: 3157.0
If we take 147 away from 154, we end up with 7.
Include the next digit (0) from the dividend after 7, then repeat: 70 / 21

Moving on to step 6:
When dividing 70 by 21, we get 3 with a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 31573.0
If we take 63 away from 70, we end up with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

On to step 7:
The number 21 fits into 70 3 times, leaving a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 31573.3
If we subtract 63 from 70, we get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Moving on to step 8:
70 divided by 21 is 3 with a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 31573.33
Subtract 63 from 70 to get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

In conclusion, the division gives 31573.33 with a balance of 0.007.