We divide 84396321 by 643
The aim is to understand the frequency of 643 in 84396321.

Going ahead to step 1:
When dividing 8 by 643, we get 0 with a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 8 to get 8.
Include the next digit (4) from the dividend after 8, then repeat: 84 / 643

On to step 2:
84 divided by 643 is 0 with a remainder of 84.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 84 leaves us with 84.
Take the next digit (3) from the dividend and append it to 84, then repeat: 843 / 643

Step 3:
643 goes into 843 1 times with a remainder of 200.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
If we take 643 away from 843, we end up with 200.
Take the next digit (9) from the dividend and append it to 200, then repeat: 2009 / 643

On to step 4:
643 goes into 2009 3 times with a remainder of 80.
Record the quotient 3 as the next digit in the result. 
Result so far: 13.0
If we subtract 1929 from 2009, we get 80.
Grab the next digit (6) from the dividend, add it to 80, then carry on: 806 / 643

Step 5:
The number 643 fits into 806 1 times, leaving a remainder of 163.
Use 1 as the next digit of our solution. 
Result so far: 131.0
Deduct 643 from 806 and we're left with 163.
Bring next digit (3) of the dividend behind the 163 and repeat the process: 1633 / 643

Step 6:
When dividing 1633 by 643, we get 2 with a remainder of 347.
Write down 2 as next digit of the result. 
Result so far: 1312.0
If we take 1286 away from 1633, we end up with 347.
Append the next digit (2) from the dividend to 347 and continue with: 3472 / 643

On to step 7:
If we divide 3472 by 643, we get 5 and a remainder of 257.
Record the quotient 5 as the next digit in the result. 
Result so far: 13125.0
The remainder is 257 after subtracting 3215 from 3472.
Include the next digit (1) from the dividend after 257, then repeat: 2571 / 643

Going ahead to step 8:
The number 643 fits into 2571 3 times, leaving a remainder of 642.
Record the quotient 3 as the next digit in the result. 
Result so far: 131253.0
Subtracting 1929 from 2571 leaves us with 642.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6420, and continue the process.

Let's proceed to step 9:
The number 643 fits into 6420 9 times, leaving a remainder of 633.
The next digit of our result is 9. 
Result so far: 131253.9
Subtracting 5787 from 6420 leaves us with 633.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6330, and continue the process.

On to step 10:
643 goes into 6330 9 times with a remainder of 543.
Write down 9 as next digit of the result. 
Result so far: 131253.99
Subtracting 5787 from 6330 leaves us with 543.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5430, and continue the process.

Our division results in 131253.99 with a remaining 0.543.