We look at the division of 97136 by 21 
The aim is to understand the frequency of 21 in 97136.

On to step 1:
21 goes into 9 0 times with a remainder of 9.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 9 after subtracting 0 from 9.
Append the next digit (7) from the dividend to 9 and continue with: 97 / 21

Moving on to step 2:
97 divided by 21 is 4 with a remainder of 13.
Use 4 as the next digit of our solution. 
Result so far: 4.0
Subtracting 84 from 97 leaves us with 13.
Grab the next digit (1) from the dividend, add it to 13, then carry on: 131 / 21

On to step 3:
131 divided by 21 is 6 with a remainder of 5.
The next digit of our result is 6. 
Result so far: 46.0
Subtracting 126 from 131 leaves us with 5.
Grab the next digit (3) from the dividend, add it to 5, then carry on: 53 / 21

Moving on to step 4:
The number 21 fits into 53 2 times, leaving a remainder of 11.
Use 2 as the next digit of our solution. 
Result so far: 462.0
If we subtract 42 from 53, we get 11.
Fetch the next digit (6) from the dividend, attach it to 11 and continue: 116 / 21

Going ahead to step 5:
The number 21 fits into 116 5 times, leaving a remainder of 11.
Use 5 as the next digit of our solution. 
Result so far: 4625.0
If we subtract 105 from 116, we get 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 6:
When dividing 110 by 21, we get 5 with a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 4625.5
If we take 105 away from 110, we end up 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.

Going ahead to step 7:
The number 21 fits into 50 2 times, leaving a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 4625.52
Deduct 42 from 50 and we're left 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 8:
21 goes into 80 3 times with a remainder of 17.
The number 3 becomes the next digit in our result. 
Result so far: 4625.523
Subtract 63 from 80 to get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Moving on to step 9:
21 goes into 170 8 times with a remainder of 2.
The next digit of our result is 8. 
Result so far: 4625.5238
Subtracting 168 from 170 leaves us 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.

Let's proceed to step 10:
If we divide 20 by 21, we get 0 and a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 4625.5238
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.

On to step 11:
200 divided by 21 is 9 with a remainder of 11.
The number 9 becomes the next digit in our result. 
Result so far: 4625.523809
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.

Going ahead to step 12:
21 can be fit into 110 5 times, resulting in a remainder of 5.
Record the quotient 5 as the next digit in the result. 
Result so far: 4625.5238095
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.

Moving on to step 13:
The number 21 fits into 50 2 times, leaving a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 4625.52380952
Deduct 42 from 50 and we're left 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.

After the division, we end up with 4625.52380952 and a remainder of 8e-09.