We divide 391620 by 4
The aim is to understand the frequency of 4 in 391620.

Advancing to step 1:
When dividing 3 by 4, we get 0 with a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 3 and we're left with 3.
Fetch the next digit (9) from the dividend, attach it to 3 and continue: 39 / 4

On to step 2:
39 divided by 4 is 9 with a remainder of 3.
Write down 9 as next digit of the result. 
Result so far: 9.0
The remainder is 3 after subtracting 36 from 39.
Include the next digit (1) from the dividend after 3, then repeat: 31 / 4

Step 3:
If we divide 31 by 4, we get 7 and a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 97.0
Subtract 28 from 31 to get 3.
Take the next digit (6) from the dividend and append it to 3, then repeat: 36 / 4

On to step 4:
4 goes into 36 9 times with a remainder of 0.
The number 9 becomes the next digit in our result. 
Result so far: 979.0
Deduct 36 from 36 and we're left with 0.
Take the next digit (2) from the dividend and append it to 0, then repeat: 2 / 4

Step 5:
4 can be fit into 2 0 times, resulting in a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 9790.0
Deduct 0 from 2 and we're left with 2.
Take the next digit (0) from the dividend and append it to 2, then repeat: 20 / 4

Step 6:
4 can be fit into 20 5 times, resulting in a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 97905.0
Subtracting 20 from 20 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.

Advancing to step 7:
4 can be fit into 0 0 times, resulting in a remainder of 0.
The next digit of our result is 0. 
Result so far: 97905.0
If we take 0 away from 0, we end up 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.

Let's proceed to step 8:
When dividing 0 by 4, we get 0 with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 97905.0
If we take 0 away from 0, we end up 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.

The final result is 97905.0 with a remainder of 0.0.