We look at the division of 57991291 by 686 
The aim is to understand the frequency of 686 in 57991291.

Going ahead to step 1:
The number 686 fits into 5 0 times, leaving a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Include the next digit (7) from the dividend after 5, then repeat: 57 / 686

Let's proceed to step 2:
If we divide 57 by 686, we get 0 and a remainder of 57.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 57 after subtracting 0 from 57.
Take the next digit (9) from the dividend and append it to 57, then repeat: 579 / 686

Let's proceed to step 3:
The number 686 fits into 579 0 times, leaving a remainder of 579.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 579, we get 579.
Append the next digit (9) from the dividend to 579 and continue with: 5799 / 686

Moving on to step 4:
5799 divided by 686 is 8 with a remainder of 311.
Put 8 as the next digit of the answer. 
Result so far: 8.0
If we subtract 5488 from 5799, we get 311.
Fetch the next digit (1) from the dividend, attach it to 311 and continue: 3111 / 686

Moving on to step 5:
When dividing 3111 by 686, we get 4 with a remainder of 367.
Write down 4 as next digit of the result. 
Result so far: 84.0
Subtracting 2744 from 3111 leaves us with 367.
Append the next digit (2) from the dividend to 367 and continue with: 3672 / 686

On to step 6:
3672 divided by 686 is 5 with a remainder of 242.
Record the quotient 5 as the next digit in the result. 
Result so far: 845.0
Deduct 3430 from 3672 and we're left with 242.
Append the next digit (9) from the dividend to 242 and continue with: 2429 / 686

Going ahead to step 7:
686 goes into 2429 3 times with a remainder of 371.
Write down 3 as next digit of the result. 
Result so far: 8453.0
The remainder is 371 after subtracting 2058 from 2429.
Include the next digit (1) from the dividend after 371, then repeat: 3711 / 686

Going ahead to step 8:
686 can be fit into 3711 5 times, resulting in a remainder of 281.
The number 5 becomes the next digit in our result. 
Result so far: 84535.0
If we take 3430 away from 3711, we end up with 281.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2810, and continue the process.

Going ahead to step 9:
The number 686 fits into 2810 4 times, leaving a remainder of 66.
The number 4 becomes the next digit in our result. 
Result so far: 84535.4
Deduct 2744 from 2810 and we're left with 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Moving on to step 10:
The number 686 fits into 660 0 times, leaving a remainder of 660.
The number 0 becomes the next digit in our result. 
Result so far: 84535.4
The remainder is 660 after subtracting 0 from 660.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6600, and continue the process.

Let's proceed to step 11:
686 goes into 6600 9 times with a remainder of 426.
Use 9 as the next digit of our solution. 
Result so far: 84535.409
The remainder is 426 after subtracting 6174 from 6600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4260, and continue the process.

Going ahead to step 12:
The number 686 fits into 4260 6 times, leaving a remainder of 144.
Record the quotient 6 as the next digit in the result. 
Result so far: 84535.4096
Subtracting 4116 from 4260 leaves us with 144.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1440, and continue the process.

Moving on to step 13:
1440 divided by 686 is 2 with a remainder of 68.
Write down 2 as next digit of the result. 
Result so far: 84535.40962
If we take 1372 away from 1440, we end up with 68.
Since there are no more digits in the dividend, we add a zero to the remainder making it 680, and continue the process.

Going ahead to step 14:
686 can be fit into 680 0 times, resulting in a remainder of 680.
Record the quotient 0 as the next digit in the result. 
Result so far: 84535.40962
Subtract 0 from 680 to get 680.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6800, and continue the process.

On to step 15:
When dividing 6800 by 686, we get 9 with a remainder of 626.
The number 9 becomes the next digit in our result. 
Result so far: 84535.4096209
Subtract 6174 from 6800 to get 626.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6260, and continue the process.

Moving on to step 16:
6260 divided by 686 is 9 with a remainder of 86.
Write down 9 as next digit of the result. 
Result so far: 84535.40962099
Deduct 6174 from 6260 and we're left with 86.
Since there are no more digits in the dividend, we add a zero to the remainder making it 860, and continue the process.

The final result is 84535.40962099 with a remainder of 8.6e-08.