We look at the division of 506981 by 15 
The aim is to understand the frequency of 15 in 506981.

Advancing to step 1:
15 goes into 5 0 times with a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Fetch the next digit (0) from the dividend, attach it to 5 and continue: 50 / 15

Advancing to step 2:
15 can be fit into 50 3 times, resulting in a remainder of 5.
Put 3 as the next digit of the answer. 
Result so far: 3.0
If we subtract 45 from 50, we get 5.
Take the next digit (6) from the dividend and append it to 5, then repeat: 56 / 15

Going ahead to step 3:
15 goes into 56 3 times with a remainder of 11.
Record the quotient 3 as the next digit in the result. 
Result so far: 33.0
Deduct 45 from 56 and we're left with 11.
Append the next digit (9) from the dividend to 11 and continue with: 119 / 15

Step 4:
The number 15 fits into 119 7 times, leaving a remainder of 14.
Use 7 as the next digit of our solution. 
Result so far: 337.0
Subtracting 105 from 119 leaves us with 14.
Grab the next digit (8) from the dividend, add it to 14, then carry on: 148 / 15

On to step 5:
When dividing 148 by 15, we get 9 with a remainder of 13.
Use 9 as the next digit of our solution. 
Result so far: 3379.0
If we take 135 away from 148, we end up with 13.
Bring next digit (1) of the dividend behind the 13 and repeat the process: 131 / 15

Advancing to step 6:
When dividing 131 by 15, we get 8 with a remainder of 11.
Put 8 as the next digit of the answer. 
Result so far: 33798.0
If we take 120 away from 131, we end up with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Moving on to step 7:
If we divide 110 by 15, we get 7 and a remainder of 5.
Put 7 as the next digit of the answer. 
Result so far: 33798.7
The remainder is 5 after subtracting 105 from 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

On to step 8:
15 goes into 50 3 times with a remainder of 5.
Put 3 as the next digit of the answer. 
Result so far: 33798.73
If we take 45 away from 50, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Step 9:
50 divided by 15 is 3 with a remainder of 5.
The next digit of our result is 3. 
Result so far: 33798.733
The remainder is 5 after subtracting 45 from 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

The quotient of the division is 33798.733, and the remainder is 0.0005.