Let's divide 17805 by 21
The aim is to understand the frequency of 21 in 17805.

Advancing to step 1:
1 divided by 21 is 0 with a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Include the next digit (7) from the dividend after 1, then repeat: 17 / 21

Step 2:
The number 21 fits into 17 0 times, leaving a remainder of 17.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 17 and we're left with 17.
Take the next digit (8) from the dividend and append it to 17, then repeat: 178 / 21

Moving on to step 3:
21 can be fit into 178 8 times, resulting in a remainder of 10.
Record the quotient 8 as the next digit in the result. 
Result so far: 8.0
Subtract 168 from 178 to get 10.
Take the next digit (0) from the dividend and append it to 10, then repeat: 100 / 21

Step 4:
21 goes into 100 4 times with a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 84.0
The remainder is 16 after subtracting 84 from 100.
Grab the next digit (5) from the dividend, add it to 16, then carry on: 165 / 21

Going ahead to step 5:
165 divided by 21 is 7 with a remainder of 18.
Record the quotient 7 as the next digit in the result. 
Result so far: 847.0
Deduct 147 from 165 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.

Moving on to step 6:
21 can be fit into 180 8 times, resulting in a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 847.8
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Going ahead to step 7:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 847.85
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.

Let's proceed to step 8:
150 divided by 21 is 7 with a remainder of 3.
Record the quotient 7 as the next digit in the result. 
Result so far: 847.857
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.

Advancing to step 9:
If we divide 30 by 21, we get 1 and a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 847.8571
Subtract 21 from 30 to get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Let's proceed to step 10:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 847.85714
Subtract 84 from 90 to get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 11:
If we divide 60 by 21, we get 2 and a remainder of 18.
The next digit of our result is 2. 
Result so far: 847.857142
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.

Step 12:
21 goes into 180 8 times with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 847.8571428
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Going ahead to step 13:
When dividing 120 by 21, we get 5 with a remainder of 15.
Use 5 as the next digit of our solution. 
Result so far: 847.85714285
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.

Our division results in 847.85714285 with a remaining 1.5e-08.