We're dividing 76170 by 21 
The aim is to understand the frequency of 21 in 76170.

Step 1:
If we divide 7 by 21, we get 0 and a remainder of 7.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 7, we get 7.
Bring next digit (6) of the dividend behind the 7 and repeat the process: 76 / 21

Let's proceed to step 2:
21 can be fit into 76 3 times, resulting in a remainder of 13.
Write down 3 as next digit of the result. 
Result so far: 3.0
Deduct 63 from 76 and we're left with 13.
Grab the next digit (1) from the dividend, add it to 13, then carry on: 131 / 21

Advancing to step 3:
21 goes into 131 6 times with a remainder of 5.
Write down 6 as next digit of the result. 
Result so far: 36.0
The remainder is 5 after subtracting 126 from 131.
Take the next digit (7) from the dividend and append it to 5, then repeat: 57 / 21

On to step 4:
The number 21 fits into 57 2 times, leaving a remainder of 15.
The number 2 becomes the next digit in our result. 
Result so far: 362.0
If we take 42 away from 57, we end up with 15.
Fetch the next digit (0) from the dividend, attach it to 15 and continue: 150 / 21

Going ahead to step 5:
The number 21 fits into 150 7 times, leaving a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 3627.0
The remainder is 3 after subtracting 147 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Going ahead to step 6:
When dividing 30 by 21, we get 1 with a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 3627.1
Subtracting 21 from 30 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 7:
If we divide 90 by 21, we get 4 and a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 3627.14
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 8:
21 can be fit into 60 2 times, resulting in a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 3627.142
Deduct 42 from 60 and we're left with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Let's proceed to step 9:
21 can be fit into 180 8 times, resulting in a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 3627.1428
If we take 168 away from 180, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 10:
If we divide 120 by 21, we get 5 and a remainder of 15.
The next digit of our result is 5. 
Result so far: 3627.14285
If we take 105 away from 120, we end up with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Step 11:
21 goes into 150 7 times with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 3627.142857
If we take 147 away from 150, we end up with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 12:
30 divided by 21 is 1 with a remainder of 9.
The next digit of our result is 1. 
Result so far: 3627.1428571
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 13:
If we divide 90 by 21, we get 4 and a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 3627.14285714
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

In conclusion, the division gives 3627.14285714 with a balance of 6e-09.