We're dividing 535310 by 21 
Let's see how many times 21 fits into 535310.

Step 1:
The number 21 fits into 5 0 times, leaving a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Append the next digit (3) from the dividend to 5 and continue with: 53 / 21

Advancing to step 2:
21 can be fit into 53 2 times, resulting in a remainder of 11.
Use 2 as the next digit of our solution. 
Result so far: 2.0
The remainder is 11 after subtracting 42 from 53.
Grab the next digit (5) from the dividend, add it to 11, then carry on: 115 / 21

Advancing to step 3:
21 goes into 115 5 times with a remainder of 10.
The next digit of our result is 5. 
Result so far: 25.0
If we take 105 away from 115, we end up with 10.
Append the next digit (3) from the dividend to 10 and continue with: 103 / 21

On to step 4:
If we divide 103 by 21, we get 4 and a remainder of 19.
The next digit of our result is 4. 
Result so far: 254.0
Subtracting 84 from 103 leaves us with 19.
Include the next digit (1) from the dividend after 19, then repeat: 191 / 21

Going ahead to step 5:
21 goes into 191 9 times with a remainder of 2.
Write down 9 as next digit of the result. 
Result so far: 2549.0
If we subtract 189 from 191, we get 2.
Take the next digit (0) from the dividend and append it to 2, then repeat: 20 / 21

On to step 6:
21 goes into 20 0 times with a remainder of 20.
The next digit of our result is 0. 
Result so far: 25490.0
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 7:
When dividing 200 by 21, we get 9 with a remainder of 11.
Put 9 as the next digit of the answer. 
Result so far: 25490.9
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 8:
When dividing 110 by 21, we get 5 with a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 25490.95
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.

Step 9:
When dividing 50 by 21, we get 2 with a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 25490.952
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.

Advancing to step 10:
80 divided by 21 is 3 with a remainder of 17.
Use 3 as the next digit of our solution. 
Result so far: 25490.9523
Subtracting 63 from 80 leaves us 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.

Going ahead to step 11:
When dividing 170 by 21, we get 8 with a remainder of 2.
Write down 8 as next digit of the result. 
Result so far: 25490.95238
Subtract 168 from 170 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Let's proceed to step 12:
21 goes into 20 0 times with a remainder of 20.
Put 0 as the next digit of the answer. 
Result so far: 25490.95238
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.

Moving on to step 13:
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: 25490.9523809
If we take 189 away from 200, we end up 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.

Moving on to step 14:
110 divided by 21 is 5 with a remainder of 5.
The number 5 becomes the next digit in our result. 
Result so far: 25490.95238095
The remainder is 5 after subtracting 105 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

The final outcome is 25490.95238095, with a leftover of 5e-09.