39966107 divided by 645 
The aim is to understand the frequency of 645 in 39966107.

Moving on to step 1:
645 can be fit into 3 0 times, resulting in a remainder of 3.
The next digit of our result is 0. 
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 / 645

Advancing to step 2:
When dividing 39 by 645, we get 0 with a remainder of 39.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 39 after subtracting 0 from 39.
Take the next digit (9) from the dividend and append it to 39, then repeat: 399 / 645

Let's proceed to step 3:
645 can be fit into 399 0 times, resulting in a remainder of 399.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 399 to get 399.
Include the next digit (6) from the dividend after 399, then repeat: 3996 / 645

On to step 4:
645 can be fit into 3996 6 times, resulting in a remainder of 126.
Record the quotient 6 as the next digit in the result. 
Result so far: 6.0
The remainder is 126 after subtracting 3870 from 3996.
Append the next digit (6) from the dividend to 126 and continue with: 1266 / 645

Step 5:
1266 divided by 645 is 1 with a remainder of 621.
Use 1 as the next digit of our solution. 
Result so far: 61.0
If we take 645 away from 1266, we end up with 621.
Include the next digit (1) from the dividend after 621, then repeat: 6211 / 645

Going ahead to step 6:
645 can be fit into 6211 9 times, resulting in a remainder of 406.
Use 9 as the next digit of our solution. 
Result so far: 619.0
Subtract 5805 from 6211 to get 406.
Fetch the next digit (0) from the dividend, attach it to 406 and continue: 4060 / 645

Going ahead to step 7:
645 goes into 4060 6 times with a remainder of 190.
Record the quotient 6 as the next digit in the result. 
Result so far: 6196.0
Subtract 3870 from 4060 to get 190.
Append the next digit (7) from the dividend to 190 and continue with: 1907 / 645

Advancing to step 8:
The number 645 fits into 1907 2 times, leaving a remainder of 617.
The number 2 becomes the next digit in our result. 
Result so far: 61962.0
If we subtract 1290 from 1907, we get 617.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6170, and continue the process.

On to step 9:
645 can be fit into 6170 9 times, resulting in a remainder of 365.
Record the quotient 9 as the next digit in the result. 
Result so far: 61962.9
Deduct 5805 from 6170 and we're left with 365.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3650, and continue the process.

Step 10:
The number 645 fits into 3650 5 times, leaving a remainder of 425.
The number 5 becomes the next digit in our result. 
Result so far: 61962.95
Subtracting 3225 from 3650 leaves us with 425.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4250, and continue the process.

Step 11:
When dividing 4250 by 645, we get 6 with a remainder of 380.
The number 6 becomes the next digit in our result. 
Result so far: 61962.956
If we take 3870 away from 4250, we end up with 380.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3800, and continue the process.

Step 12:
3800 divided by 645 is 5 with a remainder of 575.
The next digit of our result is 5. 
Result so far: 61962.9565
Deduct 3225 from 3800 and we're left with 575.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5750, and continue the process.

Step 13:
645 goes into 5750 8 times with a remainder of 590.
Record the quotient 8 as the next digit in the result. 
Result so far: 61962.95658
If we subtract 5160 from 5750, we get 590.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5900, and continue the process.

Step 14:
If we divide 5900 by 645, we get 9 and a remainder of 95.
Record the quotient 9 as the next digit in the result. 
Result so far: 61962.956589
Subtract 5805 from 5900 to get 95.
Since there are no more digits in the dividend, we add a zero to the remainder making it 950, and continue the process.

Moving on to step 15:
If we divide 950 by 645, we get 1 and a remainder of 305.
The next digit of our result is 1. 
Result so far: 61962.9565891
Deduct 645 from 950 and we're left with 305.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3050, and continue the process.

On to step 16:
When dividing 3050 by 645, we get 4 with a remainder of 470.
Record the quotient 4 as the next digit in the result. 
Result so far: 61962.95658914
Subtracting 2580 from 3050 leaves us with 470.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4700, and continue the process.

After the division, we end up with 61962.95658914 and a remainder of 4.7e-07.