We look at the division of 72281 by 21 
The aim is to understand the frequency of 21 in 72281.

Going ahead to step 1:
21 goes into 7 0 times with a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Grab the next digit (2) from the dividend, add it to 7, then carry on: 72 / 21

Step 2:
The number 21 fits into 72 3 times, leaving a remainder of 9.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Deduct 63 from 72 and we're left with 9.
Append the next digit (2) from the dividend to 9 and continue with: 92 / 21

Advancing to step 3:
The number 21 fits into 92 4 times, leaving a remainder of 8.
Write down 4 as next digit of the result. 
Result so far: 34.0
Subtract 84 from 92 to get 8.
Take the next digit (8) from the dividend and append it to 8, then repeat: 88 / 21

On to step 4:
21 goes into 88 4 times with a remainder of 4.
Use 4 as the next digit of our solution. 
Result so far: 344.0
Subtracting 84 from 88 leaves us with 4.
Take the next digit (1) from the dividend and append it to 4, then repeat: 41 / 21

Advancing to step 5:
If we divide 41 by 21, we get 1 and a remainder of 20.
Put 1 as the next digit of the answer. 
Result so far: 3441.0
If we take 21 away from 41, 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.

Advancing to step 6:
21 can be fit into 200 9 times, resulting in a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 3441.9
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.

Step 7:
21 can be fit into 110 5 times, resulting in a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 3441.95
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.

Moving on to step 8:
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: 3441.952
If we subtract 42 from 50, we get 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 9:
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: 3441.9523
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 10:
If we divide 170 by 21, we get 8 and a remainder of 2.
The next digit of our result is 8. 
Result so far: 3441.95238
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.

Moving on to step 11:
21 can be fit into 20 0 times, resulting in a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 3441.95238
Subtract 0 from 20 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.

Moving on to step 12:
If we divide 200 by 21, we get 9 and a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 3441.9523809
Subtract 189 from 200 to 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.

On to step 13:
When dividing 110 by 21, we get 5 with a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 3441.95238095
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.

In conclusion, the division gives 3441.95238095 with a balance of 5e-09.