We divide 644673 by 39
The aim is to understand the frequency of 39 in 644673.

Step 1:
If we divide 6 by 39, we get 0 and a remainder of 6.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Fetch the next digit (4) from the dividend, attach it to 6 and continue: 64 / 39

Let's proceed to step 2:
The number 39 fits into 64 1 times, leaving a remainder of 25.
Write down 1 as next digit of the result. 
Result so far: 1.0
The remainder is 25 after subtracting 39 from 64.
Append the next digit (4) from the dividend to 25 and continue with: 254 / 39

Advancing to step 3:
254 divided by 39 is 6 with a remainder of 20.
Use 6 as the next digit of our solution. 
Result so far: 16.0
Subtract 234 from 254 to get 20.
Bring next digit (6) of the dividend behind the 20 and repeat the process: 206 / 39

Moving on to step 4:
The number 39 fits into 206 5 times, leaving a remainder of 11.
Record the quotient 5 as the next digit in the result. 
Result so far: 165.0
The remainder is 11 after subtracting 195 from 206.
Take the next digit (7) from the dividend and append it to 11, then repeat: 117 / 39

Let's proceed to step 5:
39 can be fit into 117 3 times, resulting in a remainder of 0.
Record the quotient 3 as the next digit in the result. 
Result so far: 1653.0
Subtracting 117 from 117 leaves us with 0.
Grab the next digit (3) from the dividend, add it to 0, then carry on: 3 / 39

Moving on to step 6:
3 divided by 39 is 0 with a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 16530.0
Subtract 0 from 3 to get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Advancing to step 7:
39 goes into 30 0 times with a remainder of 30.
Use 0 as the next digit of our solution. 
Result so far: 16530.0
The remainder is 30 after subtracting 0 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Advancing to step 8:
300 divided by 39 is 7 with a remainder of 27.
Write down 7 as next digit of the result. 
Result so far: 16530.07
If we subtract 273 from 300, we get 27.
Since there are no more digits in the dividend, we add a zero to the remainder making it 270, and continue the process.

Let's proceed to step 9:
If we divide 270 by 39, we get 6 and a remainder of 36.
Put 6 as the next digit of the answer. 
Result so far: 16530.076
If we take 234 away from 270, we end up with 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Going ahead to step 10:
39 goes into 360 9 times with a remainder of 9.
Record the quotient 9 as the next digit in the result. 
Result so far: 16530.0769
If we take 351 away from 360, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 11:
39 can be fit into 90 2 times, resulting in a remainder of 12.
Put 2 as the next digit of the answer. 
Result so far: 16530.07692
If we subtract 78 from 90, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

On to step 12:
When dividing 120 by 39, we get 3 with a remainder of 3.
The number 3 becomes the next digit in our result. 
Result so far: 16530.076923
If we subtract 117 from 120, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 13:
30 divided by 39 is 0 with a remainder of 30.
The number 0 becomes the next digit in our result. 
Result so far: 16530.076923
Deduct 0 from 30 and we're left with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Advancing to step 14:
The number 39 fits into 300 7 times, leaving a remainder of 27.
Use 7 as the next digit of our solution. 
Result so far: 16530.07692307
The remainder is 27 after subtracting 273 from 300.
Since there are no more digits in the dividend, we add a zero to the remainder making it 270, and continue the process.

The final outcome is 16530.07692307, with a leftover of 2.7e-08.