We look at the division of 642594 by 15 
The aim is to understand the frequency of 15 in 642594.

On to step 1:
15 goes into 6 0 times with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Grab the next digit (4) from the dividend, add it to 6, then carry on: 64 / 15

Moving on to step 2:
If we divide 64 by 15, we get 4 and a remainder of 4.
Write down 4 as next digit of the result. 
Result so far: 4.0
If we take 60 away from 64, we end up with 4.
Grab the next digit (2) from the dividend, add it to 4, then carry on: 42 / 15

Advancing to step 3:
The number 15 fits into 42 2 times, leaving a remainder of 12.
Write down 2 as next digit of the result. 
Result so far: 42.0
Deduct 30 from 42 and we're left with 12.
Take the next digit (5) from the dividend and append it to 12, then repeat: 125 / 15

On to step 4:
The number 15 fits into 125 8 times, leaving a remainder of 5.
The number 8 becomes the next digit in our result. 
Result so far: 428.0
Subtracting 120 from 125 leaves us with 5.
Fetch the next digit (9) from the dividend, attach it to 5 and continue: 59 / 15

Step 5:
If we divide 59 by 15, we get 3 and a remainder of 14.
Record the quotient 3 as the next digit in the result. 
Result so far: 4283.0
The remainder is 14 after subtracting 45 from 59.
Fetch the next digit (4) from the dividend, attach it to 14 and continue: 144 / 15

Advancing to step 6:
The number 15 fits into 144 9 times, leaving a remainder of 9.
Record the quotient 9 as the next digit in the result. 
Result so far: 42839.0
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.

Moving on to step 7:
15 can be fit into 90 6 times, resulting in a remainder of 0.
Use 6 as the next digit of our solution. 
Result so far: 42839.6
Deduct 90 from 90 and we're left 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.

Going ahead to step 8:
When dividing 0 by 15, we get 0 with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 42839.6
Subtracting 0 from 0 leaves us 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.

Let's proceed to step 9:
0 divided by 15 is 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 42839.6
Deduct 0 from 0 and we're left 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.

The quotient of the division is 42839.6, and the remainder is 0.0.