437021 divided by 39 
The aim is to understand the frequency of 39 in 437021.

Advancing to step 1:
4 divided by 39 is 0 with a remainder of 4.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 4, we end up with 4.
Include the next digit (3) from the dividend after 4, then repeat: 43 / 39

Let's proceed to step 2:
If we divide 43 by 39, we get 1 and a remainder of 4.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we subtract 39 from 43, we get 4.
Grab the next digit (7) from the dividend, add it to 4, then carry on: 47 / 39

Step 3:
47 divided by 39 is 1 with a remainder of 8.
The number 1 becomes the next digit in our result. 
Result so far: 11.0
Deduct 39 from 47 and we're left with 8.
Grab the next digit (0) from the dividend, add it to 8, then carry on: 80 / 39

Moving on to step 4:
When dividing 80 by 39, we get 2 with a remainder of 2.
Record the quotient 2 as the next digit in the result. 
Result so far: 112.0
Subtract 78 from 80 to get 2.
Append the next digit (2) from the dividend to 2 and continue with: 22 / 39

Step 5:
The number 39 fits into 22 0 times, leaving a remainder of 22.
Record the quotient 0 as the next digit in the result. 
Result so far: 1120.0
If we take 0 away from 22, we end up with 22.
Bring next digit (1) of the dividend behind the 22 and repeat the process: 221 / 39

Going ahead to step 6:
The number 39 fits into 221 5 times, leaving a remainder of 26.
Use 5 as the next digit of our solution. 
Result so far: 11205.0
If we take 195 away from 221, we end up with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Step 7:
The number 39 fits into 260 6 times, leaving a remainder of 26.
Use 6 as the next digit of our solution. 
Result so far: 11205.6
Subtracting 234 from 260 leaves us with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

Moving on to step 8:
When dividing 260 by 39, we get 6 with a remainder of 26.
The next digit of our result is 6. 
Result so far: 11205.66
Deduct 234 from 260 and we're left with 26.
Since there are no more digits in the dividend, we add a zero to the remainder making it 260, and continue the process.

The final outcome is 11205.66, with a leftover of 0.026.