We look at the division of 860765 by 21 
The aim is to understand the frequency of 21 in 860765.

Step 1:
21 goes into 8 0 times with a remainder of 8.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Take the next digit (6) from the dividend and append it to 8, then repeat: 86 / 21

Let's proceed to step 2:
21 goes into 86 4 times with a remainder of 2.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
Subtracting 84 from 86 leaves us with 2.
Grab the next digit (0) from the dividend, add it to 2, then carry on: 20 / 21

Step 3:
20 divided by 21 is 0 with a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 40.0
If we take 0 away from 20, we end up with 20.
Include the next digit (7) from the dividend after 20, then repeat: 207 / 21

Step 4:
If we divide 207 by 21, we get 9 and a remainder of 18.
Use 9 as the next digit of our solution. 
Result so far: 409.0
Subtract 189 from 207 to get 18.
Bring next digit (6) of the dividend behind the 18 and repeat the process: 186 / 21

Moving on to step 5:
21 goes into 186 8 times with a remainder of 18.
Put 8 as the next digit of the answer. 
Result so far: 4098.0
If we take 168 away from 186, we end up with 18.
Append the next digit (5) from the dividend to 18 and continue with: 185 / 21

Let's proceed to step 6:
The number 21 fits into 185 8 times, leaving a remainder of 17.
Record the quotient 8 as the next digit in the result. 
Result so far: 40988.0
Subtracting 168 from 185 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 7:
21 goes into 170 8 times with a remainder of 2.
Put 8 as the next digit of the answer. 
Result so far: 40988.8
Subtract 168 from 170 to 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.

On to step 8:
When dividing 20 by 21, we get 0 with a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 40988.8
Deduct 0 from 20 and we're left 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.

Let's proceed to step 9:
When dividing 200 by 21, we get 9 with a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 40988.809
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.

On to step 10:
If we divide 110 by 21, we get 5 and a remainder of 5.
The next digit of our result is 5. 
Result so far: 40988.8095
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.

Moving on to step 11:
21 goes into 50 2 times with a remainder of 8.
Write down 2 as next digit of the result. 
Result so far: 40988.80952
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.

Let's proceed to step 12:
If we divide 80 by 21, we get 3 and a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 40988.809523
Deduct 63 from 80 and we're left 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.

Advancing to step 13:
If we divide 170 by 21, we get 8 and a remainder of 2.
Put 8 as the next digit of the answer. 
Result so far: 40988.8095238
Deduct 168 from 170 and we're left 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.

Step 14:
20 divided by 21 is 0 with a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 40988.8095238
Deduct 0 from 20 and we're left 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.

The final outcome is 40988.8095238, with a leftover of 2e-08.