399687 ÷ 51 
The aim is to understand the frequency of 51 in 399687.

Let's proceed to step 1:
3 divided by 51 is 0 with a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Include the next digit (9) from the dividend after 3, then repeat: 39 / 51

Going ahead to step 2:
When dividing 39 by 51, we get 0 with a remainder of 39.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 39, we end up with 39.
Append the next digit (9) from the dividend to 39 and continue with: 399 / 51

On to step 3:
399 divided by 51 is 7 with a remainder of 42.
Put 7 as the next digit of the answer. 
Result so far: 7.0
Deduct 357 from 399 and we're left with 42.
Take the next digit (6) from the dividend and append it to 42, then repeat: 426 / 51

Advancing to step 4:
51 can be fit into 426 8 times, resulting in a remainder of 18.
The next digit of our result is 8. 
Result so far: 78.0
If we subtract 408 from 426, we get 18.
Append the next digit (8) from the dividend to 18 and continue with: 188 / 51

Moving on to step 5:
188 divided by 51 is 3 with a remainder of 35.
The next digit of our result is 3. 
Result so far: 783.0
Deduct 153 from 188 and we're left with 35.
Bring next digit (7) of the dividend behind the 35 and repeat the process: 357 / 51

Moving on to step 6:
51 goes into 357 7 times with a remainder of 0.
The number 7 becomes the next digit in our result. 
Result so far: 7837.0
Deduct 357 from 357 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 7:
51 can be fit into 0 0 times, resulting in a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 7837.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Moving on to step 8:
When dividing 0 by 51, we get 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 7837.0
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

In conclusion, the division gives 7837.0 with a balance of 0.0.