816109 ÷ 84 
The aim is to understand the frequency of 84 in 816109.

Moving on to step 1:
If we divide 8 by 84, we get 0 and a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Append the next digit (1) from the dividend to 8 and continue with: 81 / 84

On to step 2:
84 can be fit into 81 0 times, resulting in a remainder of 81.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 81 and we're left with 81.
Grab the next digit (6) from the dividend, add it to 81, then carry on: 816 / 84

Step 3:
The number 84 fits into 816 9 times, leaving a remainder of 60.
Put 9 as the next digit of the answer. 
Result so far: 9.0
If we subtract 756 from 816, we get 60.
Grab the next digit (1) from the dividend, add it to 60, then carry on: 601 / 84

Advancing to step 4:
601 divided by 84 is 7 with a remainder of 13.
Use 7 as the next digit of our solution. 
Result so far: 97.0
If we take 588 away from 601, we end up with 13.
Include the next digit (0) from the dividend after 13, then repeat: 130 / 84

On to step 5:
84 can be fit into 130 1 times, resulting in a remainder of 46.
The next digit of our result is 1. 
Result so far: 971.0
If we take 84 away from 130, we end up with 46.
Include the next digit (9) from the dividend after 46, then repeat: 469 / 84

Going ahead to step 6:
84 can be fit into 469 5 times, resulting in a remainder of 49.
Put 5 as the next digit of the answer. 
Result so far: 9715.0
Deduct 420 from 469 and we're left with 49.
Since there are no more digits in the dividend, we add a zero to the remainder making it 490, and continue the process.

On to step 7:
84 can be fit into 490 5 times, resulting in a remainder of 70.
Use 5 as the next digit of our solution. 
Result so far: 9715.5
If we take 420 away from 490, we end up with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Moving on to step 8:
The number 84 fits into 700 8 times, leaving a remainder of 28.
Use 8 as the next digit of our solution. 
Result so far: 9715.58
Deduct 672 from 700 and we're left with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Advancing to step 9:
If we divide 280 by 84, we get 3 and a remainder of 28.
Use 3 as the next digit of our solution. 
Result so far: 9715.583
Subtracting 252 from 280 leaves us with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Step 10:
280 divided by 84 is 3 with a remainder of 28.
Put 3 as the next digit of the answer. 
Result so far: 9715.5833
If we subtract 252 from 280, we get 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

After the division, we end up with 9715.5833 and a remainder of 0.00028.