Let's divide 646913 by 81
The aim is to understand the frequency of 81 in 646913.

Step 1:
6 divided by 81 is 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 81

On to step 2:
81 can be fit into 64 0 times, resulting in a remainder of 64.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 64 after subtracting 0 from 64.
Include the next digit (6) from the dividend after 64, then repeat: 646 / 81

Moving on to step 3:
81 can be fit into 646 7 times, resulting in a remainder of 79.
Use 7 as the next digit of our solution. 
Result so far: 7.0
The remainder is 79 after subtracting 567 from 646.
Append the next digit (9) from the dividend to 79 and continue with: 799 / 81

Let's proceed to step 4:
81 goes into 799 9 times with a remainder of 70.
Record the quotient 9 as the next digit in the result. 
Result so far: 79.0
The remainder is 70 after subtracting 729 from 799.
Bring next digit (1) of the dividend behind the 70 and repeat the process: 701 / 81

Moving on to step 5:
81 can be fit into 701 8 times, resulting in a remainder of 53.
Put 8 as the next digit of the answer. 
Result so far: 798.0
Deduct 648 from 701 and we're left with 53.
Fetch the next digit (3) from the dividend, attach it to 53 and continue: 533 / 81

On to step 6:
81 goes into 533 6 times with a remainder of 47.
The number 6 becomes the next digit in our result. 
Result so far: 7986.0
The remainder is 47 after subtracting 486 from 533.
Since there are no more digits in the dividend, we add a zero to the remainder making it 470, and continue the process.

Advancing to step 7:
When dividing 470 by 81, we get 5 with a remainder of 65.
Put 5 as the next digit of the answer. 
Result so far: 7986.5
Subtracting 405 from 470 leaves us with 65.
Since there are no more digits in the dividend, we add a zero to the remainder making it 650, and continue the process.

Step 8:
When dividing 650 by 81, we get 8 with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 7986.58
If we take 648 away from 650, we end up 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.

Going ahead to step 9:
When dividing 20 by 81, we get 0 with a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 7986.58
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.

Going ahead to step 10:
200 divided by 81 is 2 with a remainder of 38.
Put 2 as the next digit of the answer. 
Result so far: 7986.5802
Subtracting 162 from 200 leaves us with 38.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

Step 11:
The number 81 fits into 380 4 times, leaving a remainder of 56.
Use 4 as the next digit of our solution. 
Result so far: 7986.58024
If we subtract 324 from 380, we get 56.
Since there are no more digits in the dividend, we add a zero to the remainder making it 560, and continue the process.

Advancing to step 12:
81 can be fit into 560 6 times, resulting in a remainder of 74.
The number 6 becomes the next digit in our result. 
Result so far: 7986.580246
Subtract 486 from 560 to get 74.
Since there are no more digits in the dividend, we add a zero to the remainder making it 740, and continue the process.

On to step 13:
740 divided by 81 is 9 with a remainder of 11.
Use 9 as the next digit of our solution. 
Result so far: 7986.5802469
Deduct 729 from 740 and we're left with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Step 14:
If we divide 110 by 81, we get 1 and a remainder of 29.
Put 1 as the next digit of the answer. 
Result so far: 7986.58024691
If we subtract 81 from 110, we get 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

The quotient of the division is 7986.58024691, and the remainder is 2.9e-08.