16489343 divided by 15 
The aim is to understand the frequency of 15 in 16489343.

Step 1:
When dividing 1 by 15, we get 0 with a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Include the next digit (6) from the dividend after 1, then repeat: 16 / 15

Let's proceed to step 2:
If we divide 16 by 15, we get 1 and a remainder of 1.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Subtract 15 from 16 to get 1.
Include the next digit (4) from the dividend after 1, then repeat: 14 / 15

Moving on to step 3:
15 can be fit into 14 0 times, resulting in a remainder of 14.
Write down 0 as next digit of the result. 
Result so far: 10.0
If we take 0 away from 14, we end up with 14.
Append the next digit (8) from the dividend to 14 and continue with: 148 / 15

Let's proceed to step 4:
15 can be fit into 148 9 times, resulting in a remainder of 13.
Put 9 as the next digit of the answer. 
Result so far: 109.0
The remainder is 13 after subtracting 135 from 148.
Take the next digit (9) from the dividend and append it to 13, then repeat: 139 / 15

Step 5:
The number 15 fits into 139 9 times, leaving a remainder of 4.
Write down 9 as next digit of the result. 
Result so far: 1099.0
Subtracting 135 from 139 leaves us with 4.
Include the next digit (3) from the dividend after 4, then repeat: 43 / 15

Moving on to step 6:
15 can be fit into 43 2 times, resulting in a remainder of 13.
Record the quotient 2 as the next digit in the result. 
Result so far: 10992.0
The remainder is 13 after subtracting 30 from 43.
Bring next digit (4) of the dividend behind the 13 and repeat the process: 134 / 15

Going ahead to step 7:
The number 15 fits into 134 8 times, leaving a remainder of 14.
Write down 8 as next digit of the result. 
Result so far: 109928.0
Deduct 120 from 134 and we're left with 14.
Grab the next digit (3) from the dividend, add it to 14, then carry on: 143 / 15

Moving on to step 8:
If we divide 143 by 15, we get 9 and a remainder of 8.
The number 9 becomes the next digit in our result. 
Result so far: 1099289.0
Subtracting 135 from 143 leaves us with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Step 9:
15 goes into 80 5 times with a remainder of 5.
The next digit of our result is 5. 
Result so far: 1099289.5
Subtract 75 from 80 to get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Moving on to step 10:
15 can be fit into 50 3 times, resulting in a remainder of 5.
The number 3 becomes the next digit in our result. 
Result so far: 1099289.53
If we subtract 45 from 50, we get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Moving on to step 11:
15 can be fit into 50 3 times, resulting in a remainder of 5.
The next digit of our result is 3. 
Result so far: 1099289.533
If we subtract 45 from 50, we get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

The final outcome is 1099289.533, with a leftover of 0.0005.