513245 divided by 21 
We're looking to find how many times 21 goes into 513245.

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

Moving on to step 2:
When dividing 51 by 21, we get 2 with a remainder of 9.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
If we take 42 away from 51, we end up with 9.
Append the next digit (3) from the dividend to 9 and continue with: 93 / 21

On to step 3:
If we divide 93 by 21, we get 4 and a remainder of 9.
Write down 4 as next digit of the result. 
Result so far: 24.0
The remainder is 9 after subtracting 84 from 93.
Grab the next digit (2) from the dividend, add it to 9, then carry on: 92 / 21

Step 4:
When dividing 92 by 21, we get 4 with a remainder of 8.
Put 4 as the next digit of the answer. 
Result so far: 244.0
If we take 84 away from 92, we end up with 8.
Take the next digit (4) from the dividend and append it to 8, then repeat: 84 / 21

Going ahead to step 5:
When dividing 84 by 21, we get 4 with a remainder of 0.
Use 4 as the next digit of our solution. 
Result so far: 2444.0
Deduct 84 from 84 and we're left with 0.
Bring next digit (5) of the dividend behind the 0 and repeat the process: 5 / 21

Step 6:
If we divide 5 by 21, we get 0 and a remainder of 5.
Use 0 as the next digit of our solution. 
Result so far: 24440.0
Subtract 0 from 5 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.

Step 7:
50 divided by 21 is 2 with a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 24440.2
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.

Step 8:
The number 21 fits into 80 3 times, leaving a remainder of 17.
The number 3 becomes the next digit in our result. 
Result so far: 24440.23
If we take 63 away from 80, we end up 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.

On to step 9:
When dividing 170 by 21, we get 8 with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 24440.238
If we subtract 168 from 170, we 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.

Step 10:
When dividing 20 by 21, we get 0 with a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 24440.238
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.

Going ahead to step 11:
When dividing 200 by 21, we get 9 with a remainder of 11.
Write down 9 as next digit of the result. 
Result so far: 24440.23809
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 12:
110 divided by 21 is 5 with a remainder of 5.
The next digit of our result is 5. 
Result so far: 24440.238095
Subtracting 105 from 110 leaves us 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.

Let's proceed to step 13:
When dividing 50 by 21, we get 2 with a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 24440.2380952
If we take 42 away from 50, we end up 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.

Going ahead to step 14:
80 divided by 21 is 3 with a remainder of 17.
The next digit of our result is 3. 
Result so far: 24440.23809523
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.

Our division results in 24440.23809523 with a remaining 1.7e-08.