13628 divided by 21 
The aim is to understand the frequency of 21 in 13628.

Moving on to step 1:
21 can be fit into 1 0 times, resulting in a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Take the next digit (3) from the dividend and append it to 1, then repeat: 13 / 21

Moving on to step 2:
13 divided by 21 is 0 with a remainder of 13.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 13 leaves us with 13.
Grab the next digit (6) from the dividend, add it to 13, then carry on: 136 / 21

Step 3:
21 goes into 136 6 times with a remainder of 10.
The next digit of our result is 6. 
Result so far: 6.0
Subtracting 126 from 136 leaves us with 10.
Append the next digit (2) from the dividend to 10 and continue with: 102 / 21

Going ahead to step 4:
When dividing 102 by 21, we get 4 with a remainder of 18.
Write down 4 as next digit of the result. 
Result so far: 64.0
Subtracting 84 from 102 leaves us with 18.
Grab the next digit (8) from the dividend, add it to 18, then carry on: 188 / 21

Step 5:
21 goes into 188 8 times with a remainder of 20.
Write down 8 as next digit of the result. 
Result so far: 648.0
Subtract 168 from 188 to get 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 6:
When dividing 200 by 21, we get 9 with a remainder of 11.
Use 9 as the next digit of our solution. 
Result so far: 648.9
Deduct 189 from 200 and we're left 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.

Let's proceed to step 7:
When dividing 110 by 21, we get 5 with a remainder of 5.
The next digit of our result is 5. 
Result so far: 648.95
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.

On to step 8:
21 can be fit into 50 2 times, resulting in a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 648.952
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 9:
If we divide 80 by 21, we get 3 and a remainder of 17.
The next digit of our result is 3. 
Result so far: 648.9523
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.

Step 10:
When dividing 170 by 21, we get 8 with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 648.95238
If we take 168 away from 170, we end up with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Advancing to step 11:
The number 21 fits into 20 0 times, leaving a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 648.95238
If we take 0 away from 20, we end up 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 12:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 648.9523809
Deduct 189 from 200 and we're left 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.

Advancing to step 13:
The number 21 fits into 110 5 times, leaving a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 648.95238095
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.

The quotient of the division is 648.95238095, and the remainder is 5e-09.