We look at the division of 854983 by 21 
The aim is to understand the frequency of 21 in 854983.

Let's proceed to step 1:
The number 21 fits into 8 0 times, leaving a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 8 and we're left with 8.
Append the next digit (5) from the dividend to 8 and continue with: 85 / 21

Advancing to step 2:
If we divide 85 by 21, we get 4 and a remainder of 1.
The next digit of our result is 4. 
Result so far: 4.0
Subtract 84 from 85 to get 1.
Grab the next digit (4) from the dividend, add it to 1, then carry on: 14 / 21

Step 3:
21 goes into 14 0 times with a remainder of 14.
The number 0 becomes the next digit in our result. 
Result so far: 40.0
The remainder is 14 after subtracting 0 from 14.
Take the next digit (9) from the dividend and append it to 14, then repeat: 149 / 21

Step 4:
When dividing 149 by 21, we get 7 with a remainder of 2.
Record the quotient 7 as the next digit in the result. 
Result so far: 407.0
If we subtract 147 from 149, we get 2.
Include the next digit (8) from the dividend after 2, then repeat: 28 / 21

Step 5:
21 goes into 28 1 times with a remainder of 7.
Record the quotient 1 as the next digit in the result. 
Result so far: 4071.0
If we subtract 21 from 28, we get 7.
Fetch the next digit (3) from the dividend, attach it to 7 and continue: 73 / 21

Advancing to step 6:
21 can be fit into 73 3 times, resulting in a remainder of 10.
Use 3 as the next digit of our solution. 
Result so far: 40713.0
Subtracting 63 from 73 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 7:
If we divide 100 by 21, we get 4 and a remainder of 16.
The next digit of our result is 4. 
Result so far: 40713.4
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 8:
160 divided by 21 is 7 with a remainder of 13.
Put 7 as the next digit of the answer. 
Result so far: 40713.47
Subtract 147 from 160 to get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Advancing to step 9:
21 goes into 130 6 times with a remainder of 4.
The next digit of our result is 6. 
Result so far: 40713.476
If we subtract 126 from 130, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 10:
40 divided by 21 is 1 with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 40713.4761
Deduct 21 from 40 and we're left with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 11:
21 goes into 190 9 times with a remainder of 1.
Write down 9 as next digit of the result. 
Result so far: 40713.47619
Subtract 189 from 190 to get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 12:
21 can be fit into 10 0 times, resulting in a remainder of 10.
The next digit of our result is 0. 
Result so far: 40713.47619
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Going ahead to step 13:
The number 21 fits into 100 4 times, leaving a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 40713.4761904
Deduct 84 from 100 and we're left with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Advancing to step 14:
21 can be fit into 160 7 times, resulting in a remainder of 13.
The next digit of our result is 7. 
Result so far: 40713.47619047
Deduct 147 from 160 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

The final outcome is 40713.47619047, with a leftover of 1.3e-08.