We look at the division of 69835159 by 643 
The aim is to understand the frequency of 643 in 69835159.

Step 1:
When dividing 6 by 643, we get 0 with a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Fetch the next digit (9) from the dividend, attach it to 6 and continue: 69 / 643

On to step 2:
The number 643 fits into 69 0 times, leaving a remainder of 69.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 69 to get 69.
Take the next digit (8) from the dividend and append it to 69, then repeat: 698 / 643

Moving on to step 3:
643 can be fit into 698 1 times, resulting in a remainder of 55.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Subtract 643 from 698 to get 55.
Take the next digit (3) from the dividend and append it to 55, then repeat: 553 / 643

Let's proceed to step 4:
When dividing 553 by 643, we get 0 with a remainder of 553.
Put 0 as the next digit of the answer. 
Result so far: 10.0
Deduct 0 from 553 and we're left with 553.
Fetch the next digit (5) from the dividend, attach it to 553 and continue: 5535 / 643

On to step 5:
The number 643 fits into 5535 8 times, leaving a remainder of 391.
Write down 8 as next digit of the result. 
Result so far: 108.0
The remainder is 391 after subtracting 5144 from 5535.
Include the next digit (1) from the dividend after 391, then repeat: 3911 / 643

Going ahead to step 6:
643 can be fit into 3911 6 times, resulting in a remainder of 53.
Use 6 as the next digit of our solution. 
Result so far: 1086.0
Deduct 3858 from 3911 and we're left with 53.
Take the next digit (5) from the dividend and append it to 53, then repeat: 535 / 643

Going ahead to step 7:
If we divide 535 by 643, we get 0 and a remainder of 535.
Record the quotient 0 as the next digit in the result. 
Result so far: 10860.0
If we take 0 away from 535, we end up with 535.
Bring next digit (9) of the dividend behind the 535 and repeat the process: 5359 / 643

Let's proceed to step 8:
If we divide 5359 by 643, we get 8 and a remainder of 215.
Put 8 as the next digit of the answer. 
Result so far: 108608.0
If we take 5144 away from 5359, we end up with 215.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2150, and continue the process.

Step 9:
When dividing 2150 by 643, we get 3 with a remainder of 221.
Write down 3 as next digit of the result. 
Result so far: 108608.3
Deduct 1929 from 2150 and we're left with 221.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2210, and continue the process.

Step 10:
When dividing 2210 by 643, we get 3 with a remainder of 281.
The next digit of our result is 3. 
Result so far: 108608.33
Subtracting 1929 from 2210 leaves us with 281.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2810, and continue the process.

The final outcome is 108608.33, with a leftover of 0.281.