Let's divide 39953664 by 643
The aim is to understand the frequency of 643 in 39953664.

Moving on to step 1:
When dividing 3 by 643, we get 0 with a remainder of 3.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 643

Moving on to step 2:
The number 643 fits into 39 0 times, leaving a remainder of 39.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 39 leaves us with 39.
Include the next digit (9) from the dividend after 39, then repeat: 399 / 643

On to step 3:
When dividing 399 by 643, we get 0 with a remainder of 399.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 399, we end up with 399.
Grab the next digit (5) from the dividend, add it to 399, then carry on: 3995 / 643

Going ahead to step 4:
The number 643 fits into 3995 6 times, leaving a remainder of 137.
Put 6 as the next digit of the answer. 
Result so far: 6.0
Subtracting 3858 from 3995 leaves us with 137.
Grab the next digit (3) from the dividend, add it to 137, then carry on: 1373 / 643

Step 5:
When dividing 1373 by 643, we get 2 with a remainder of 87.
Put 2 as the next digit of the answer. 
Result so far: 62.0
If we take 1286 away from 1373, we end up with 87.
Bring next digit (6) of the dividend behind the 87 and repeat the process: 876 / 643

Advancing to step 6:
876 divided by 643 is 1 with a remainder of 233.
The number 1 becomes the next digit in our result. 
Result so far: 621.0
Deduct 643 from 876 and we're left with 233.
Grab the next digit (6) from the dividend, add it to 233, then carry on: 2336 / 643

Step 7:
The number 643 fits into 2336 3 times, leaving a remainder of 407.
Use 3 as the next digit of our solution. 
Result so far: 6213.0
Deduct 1929 from 2336 and we're left with 407.
Grab the next digit (4) from the dividend, add it to 407, then carry on: 4074 / 643

Going ahead to step 8:
4074 divided by 643 is 6 with a remainder of 216.
Put 6 as the next digit of the answer. 
Result so far: 62136.0
If we take 3858 away from 4074, we end up with 216.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2160, and continue the process.

Moving on to step 9:
The number 643 fits into 2160 3 times, leaving a remainder of 231.
Put 3 as the next digit of the answer. 
Result so far: 62136.3
Subtracting 1929 from 2160 leaves us with 231.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2310, and continue the process.

Advancing to step 10:
The number 643 fits into 2310 3 times, leaving a remainder of 381.
Record the quotient 3 as the next digit in the result. 
Result so far: 62136.33
Subtracting 1929 from 2310 leaves us with 381.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3810, and continue the process.

The final result is 62136.33 with a remainder of 0.381.