We're dividing 86987569 by 603 
The aim is to understand the frequency of 603 in 86987569.

Let's proceed to step 1:
When dividing 8 by 603, we get 0 with a remainder of 8.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Include the next digit (6) from the dividend after 8, then repeat: 86 / 603

On to step 2:
603 goes into 86 0 times with a remainder of 86.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 86 and we're left with 86.
Grab the next digit (9) from the dividend, add it to 86, then carry on: 869 / 603

Step 3:
The number 603 fits into 869 1 times, leaving a remainder of 266.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtracting 603 from 869 leaves us with 266.
Fetch the next digit (8) from the dividend, attach it to 266 and continue: 2668 / 603

Advancing to step 4:
When dividing 2668 by 603, we get 4 with a remainder of 256.
Put 4 as the next digit of the answer. 
Result so far: 14.0
Deduct 2412 from 2668 and we're left with 256.
Grab the next digit (7) from the dividend, add it to 256, then carry on: 2567 / 603

Let's proceed to step 5:
The number 603 fits into 2567 4 times, leaving a remainder of 155.
The number 4 becomes the next digit in our result. 
Result so far: 144.0
The remainder is 155 after subtracting 2412 from 2567.
Bring next digit (5) of the dividend behind the 155 and repeat the process: 1555 / 603

Step 6:
The number 603 fits into 1555 2 times, leaving a remainder of 349.
The next digit of our result is 2. 
Result so far: 1442.0
If we subtract 1206 from 1555, we get 349.
Grab the next digit (6) from the dividend, add it to 349, then carry on: 3496 / 603

Step 7:
The number 603 fits into 3496 5 times, leaving a remainder of 481.
The next digit of our result is 5. 
Result so far: 14425.0
Deduct 3015 from 3496 and we're left with 481.
Append the next digit (9) from the dividend to 481 and continue with: 4819 / 603

Going ahead to step 8:
If we divide 4819 by 603, we get 7 and a remainder of 598.
Put 7 as the next digit of the answer. 
Result so far: 144257.0
The remainder is 598 after subtracting 4221 from 4819.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5980, and continue the process.

Step 9:
The number 603 fits into 5980 9 times, leaving a remainder of 553.
Put 9 as the next digit of the answer. 
Result so far: 144257.9
Subtract 5427 from 5980 to get 553.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5530, and continue the process.

Advancing to step 10:
The number 603 fits into 5530 9 times, leaving a remainder of 103.
Put 9 as the next digit of the answer. 
Result so far: 144257.99
Deduct 5427 from 5530 and we're left with 103.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1030, and continue the process.

The quotient of the division is 144257.99, and the remainder is 0.103.