100644 ÷ 15 
The aim is to understand the frequency of 15 in 100644.

Going ahead to step 1:
1 divided by 15 is 0 with a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Append the next digit (0) from the dividend to 1 and continue with: 10 / 15

Moving on to step 2:
15 goes into 10 0 times with a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 10 to get 10.
Include the next digit (0) from the dividend after 10, then repeat: 100 / 15

Going ahead to step 3:
The number 15 fits into 100 6 times, leaving a remainder of 10.
Record the quotient 6 as the next digit in the result. 
Result so far: 6.0
The remainder is 10 after subtracting 90 from 100.
Fetch the next digit (6) from the dividend, attach it to 10 and continue: 106 / 15

Advancing to step 4:
When dividing 106 by 15, we get 7 with a remainder of 1.
Record the quotient 7 as the next digit in the result. 
Result so far: 67.0
If we subtract 105 from 106, we get 1.
Grab the next digit (4) from the dividend, add it to 1, then carry on: 14 / 15

Advancing to step 5:
15 goes into 14 0 times with a remainder of 14.
Record the quotient 0 as the next digit in the result. 
Result so far: 670.0
The remainder is 14 after subtracting 0 from 14.
Fetch the next digit (4) from the dividend, attach it to 14 and continue: 144 / 15

Step 6:
If we divide 144 by 15, we get 9 and a remainder of 9.
The number 9 becomes the next digit in our result. 
Result so far: 6709.0
If we take 135 away from 144, 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.

Step 7:
The number 15 fits into 90 6 times, leaving a remainder of 0.
Write down 6 as next digit of the result. 
Result so far: 6709.6
Subtract 90 from 90 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 8:
15 goes into 0 0 times with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 6709.6
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 9:
The number 15 fits into 0 0 times, leaving a remainder of 0.
The next digit of our result is 0. 
Result so far: 6709.6
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

In conclusion, the division gives 6709.6 with a balance of 0.0.