153363 ÷ 21 
The aim is to understand the frequency of 21 in 153363.

Step 1:
If we divide 1 by 21, we get 0 and a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Bring next digit (5) of the dividend behind the 1 and repeat the process: 15 / 21

Advancing to step 2:
21 can be fit into 15 0 times, resulting in a remainder of 15.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 15, we end up with 15.
Fetch the next digit (3) from the dividend, attach it to 15 and continue: 153 / 21

On to step 3:
21 can be fit into 153 7 times, resulting in a remainder of 6.
Record the quotient 7 as the next digit in the result. 
Result so far: 7.0
Subtract 147 from 153 to get 6.
Take the next digit (3) from the dividend and append it to 6, then repeat: 63 / 21

On to step 4:
The number 21 fits into 63 3 times, leaving a remainder of 0.
Write down 3 as next digit of the result. 
Result so far: 73.0
If we take 63 away from 63, we end up with 0.
Fetch the next digit (6) from the dividend, attach it to 0 and continue: 6 / 21

Step 5:
The number 21 fits into 6 0 times, leaving a remainder of 6.
Use 0 as the next digit of our solution. 
Result so far: 730.0
Subtracting 0 from 6 leaves us with 6.
Take the next digit (3) from the dividend and append it to 6, then repeat: 63 / 21

Let's proceed to step 6:
21 can be fit into 63 3 times, resulting in a remainder of 0.
The next digit of our result is 3. 
Result so far: 7303.0
The remainder is 0 after subtracting 63 from 63.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 7:
21 goes into 0 0 times with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 7303.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 8:
21 can be fit into 0 0 times, resulting in a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 7303.0
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

In conclusion, the division gives 7303.0 with a balance of 0.0.