We look at the division of 391357 by 77 
The aim is to understand the frequency of 77 in 391357.

Advancing to step 1:
If we divide 3 by 77, we get 0 and a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 3, we end up with 3.
Fetch the next digit (9) from the dividend, attach it to 3 and continue: 39 / 77

Let's proceed to step 2:
If we divide 39 by 77, we get 0 and a remainder of 39.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 39, we get 39.
Include the next digit (1) from the dividend after 39, then repeat: 391 / 77

Let's proceed to step 3:
77 goes into 391 5 times with a remainder of 6.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
Subtract 385 from 391 to get 6.
Include the next digit (3) from the dividend after 6, then repeat: 63 / 77

Going ahead to step 4:
The number 77 fits into 63 0 times, leaving a remainder of 63.
Write down 0 as next digit of the result. 
Result so far: 50.0
Deduct 0 from 63 and we're left with 63.
Take the next digit (5) from the dividend and append it to 63, then repeat: 635 / 77

Going ahead to step 5:
If we divide 635 by 77, we get 8 and a remainder of 19.
The number 8 becomes the next digit in our result. 
Result so far: 508.0
Subtracting 616 from 635 leaves us with 19.
Append the next digit (7) from the dividend to 19 and continue with: 197 / 77

Going ahead to step 6:
77 can be fit into 197 2 times, resulting in a remainder of 43.
Record the quotient 2 as the next digit in the result. 
Result so far: 5082.0
Subtract 154 from 197 to get 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

On to step 7:
The number 77 fits into 430 5 times, leaving a remainder of 45.
Record the quotient 5 as the next digit in the result. 
Result so far: 5082.5
If we take 385 away from 430, we end up with 45.
Since there are no more digits in the dividend, we add a zero to the remainder making it 450, and continue the process.

Let's proceed to step 8:
The number 77 fits into 450 5 times, leaving a remainder of 65.
Use 5 as the next digit of our solution. 
Result so far: 5082.55
The remainder is 65 after subtracting 385 from 450.
Since there are no more digits in the dividend, we add a zero to the remainder making it 650, and continue the process.

The final outcome is 5082.55, with a leftover of 0.065.