We look at the division of 510433 by 21 
We want to divide 510433 by 21.

Advancing to step 1:
The number 21 fits into 5 0 times, leaving a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 5, we end up with 5.
Fetch the next digit (1) from the dividend, attach it to 5 and continue: 51 / 21

Moving on to step 2:
When dividing 51 by 21, we get 2 with a remainder of 9.
Write down 2 as next digit of the result. 
Result so far: 2.0
Deduct 42 from 51 and we're left with 9.
Grab the next digit (0) from the dividend, add it to 9, then carry on: 90 / 21

Going ahead to step 3:
If we divide 90 by 21, we get 4 and a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 24.0
If we subtract 84 from 90, we get 6.
Take the next digit (4) from the dividend and append it to 6, then repeat: 64 / 21

Advancing to step 4:
21 can be fit into 64 3 times, resulting in a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 243.0
If we take 63 away from 64, we end up with 1.
Include the next digit (3) from the dividend after 1, then repeat: 13 / 21

Moving on to step 5:
If we divide 13 by 21, we get 0 and a remainder of 13.
Put 0 as the next digit of the answer. 
Result so far: 2430.0
The remainder is 13 after subtracting 0 from 13.
Append the next digit (3) from the dividend to 13 and continue with: 133 / 21

Advancing to step 6:
The number 21 fits into 133 6 times, leaving a remainder of 7.
The number 6 becomes the next digit in our result. 
Result so far: 24306.0
Subtract 126 from 133 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.

Step 7:
21 goes into 70 3 times with a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 24306.3
Subtracting 63 from 70 leaves us 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.

Step 8:
21 can be fit into 70 3 times, resulting in a remainder of 7.
Record the quotient 3 as the next digit in the result. 
Result so far: 24306.33
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.

In conclusion, the division gives 24306.33 with a balance of 0.007.