We're dividing 3925879 by 691 
The aim is to understand the frequency of 691 in 3925879.

Step 1:
When dividing 3 by 691, we get 0 with a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 3 to get 3.
Grab the next digit (9) from the dividend, add it to 3, then carry on: 39 / 691

Step 2:
The number 691 fits into 39 0 times, leaving a remainder of 39.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 39, we end up with 39.
Take the next digit (2) from the dividend and append it to 39, then repeat: 392 / 691

Let's proceed to step 3:
392 divided by 691 is 0 with a remainder of 392.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 392 to get 392.
Fetch the next digit (5) from the dividend, attach it to 392 and continue: 3925 / 691

Let's proceed to step 4:
When dividing 3925 by 691, we get 5 with a remainder of 470.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
If we take 3455 away from 3925, we end up with 470.
Take the next digit (8) from the dividend and append it to 470, then repeat: 4708 / 691

Step 5:
If we divide 4708 by 691, we get 6 and a remainder of 562.
The number 6 becomes the next digit in our result. 
Result so far: 56.0
Deduct 4146 from 4708 and we're left with 562.
Fetch the next digit (7) from the dividend, attach it to 562 and continue: 5627 / 691

Step 6:
5627 divided by 691 is 8 with a remainder of 99.
Use 8 as the next digit of our solution. 
Result so far: 568.0
If we subtract 5528 from 5627, we get 99.
Fetch the next digit (9) from the dividend, attach it to 99 and continue: 999 / 691

Advancing to step 7:
691 can be fit into 999 1 times, resulting in a remainder of 308.
The next digit of our result is 1. 
Result so far: 5681.0
Subtract 691 from 999 to get 308.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3080, and continue the process.

On to step 8:
691 can be fit into 3080 4 times, resulting in a remainder of 316.
The number 4 becomes the next digit in our result. 
Result so far: 5681.4
The remainder is 316 after subtracting 2764 from 3080.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3160, and continue the process.

On to step 9:
The number 691 fits into 3160 4 times, leaving a remainder of 396.
Write down 4 as next digit of the result. 
Result so far: 5681.44
Subtract 2764 from 3160 to get 396.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3960, and continue the process.

In conclusion, the division gives 5681.44 with a balance of 0.396.