5154621 divided by 503 
The aim is to understand the frequency of 503 in 5154621.

Advancing to step 1:
503 can be fit into 5 0 times, resulting in a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 503

On to step 2:
If we divide 51 by 503, we get 0 and a remainder of 51.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 51 and we're left with 51.
Bring next digit (5) of the dividend behind the 51 and repeat the process: 515 / 503

Advancing to step 3:
The number 503 fits into 515 1 times, leaving a remainder of 12.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
The remainder is 12 after subtracting 503 from 515.
Fetch the next digit (4) from the dividend, attach it to 12 and continue: 124 / 503

Moving on to step 4:
124 divided by 503 is 0 with a remainder of 124.
The next digit of our result is 0. 
Result so far: 10.0
Subtract 0 from 124 to get 124.
Append the next digit (6) from the dividend to 124 and continue with: 1246 / 503

Moving on to step 5:
If we divide 1246 by 503, we get 2 and a remainder of 240.
Record the quotient 2 as the next digit in the result. 
Result so far: 102.0
Subtracting 1006 from 1246 leaves us with 240.
Include the next digit (2) from the dividend after 240, then repeat: 2402 / 503

Going ahead to step 6:
2402 divided by 503 is 4 with a remainder of 390.
Put 4 as the next digit of the answer. 
Result so far: 1024.0
The remainder is 390 after subtracting 2012 from 2402.
Grab the next digit (1) from the dividend, add it to 390, then carry on: 3901 / 503

Step 7:
If we divide 3901 by 503, we get 7 and a remainder of 380.
Record the quotient 7 as the next digit in the result. 
Result so far: 10247.0
Subtract 3521 from 3901 to get 380.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3800, and continue the process.

Advancing to step 8:
3800 divided by 503 is 7 with a remainder of 279.
The number 7 becomes the next digit in our result. 
Result so far: 10247.7
Subtracting 3521 from 3800 leaves us with 279.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2790, and continue the process.

Step 9:
If we divide 2790 by 503, we get 5 and a remainder of 275.
Put 5 as the next digit of the answer. 
Result so far: 10247.75
Deduct 2515 from 2790 and we're left with 275.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2750, and continue the process.

Step 10:
If we divide 2750 by 503, we get 5 and a remainder of 235.
Use 5 as the next digit of our solution. 
Result so far: 10247.755
Subtract 2515 from 2750 to get 235.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2350, and continue the process.

The quotient of the division is 10247.755, and the remainder is 0.0235.