We look at the division of 74856099 by 621 
The aim is to understand the frequency of 621 in 74856099.

Let's proceed to step 1:
621 goes into 7 0 times with a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Bring next digit (4) of the dividend behind the 7 and repeat the process: 74 / 621

Moving on to step 2:
When dividing 74 by 621, we get 0 with a remainder of 74.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 74 leaves us with 74.
Include the next digit (8) from the dividend after 74, then repeat: 748 / 621

On to step 3:
When dividing 748 by 621, we get 1 with a remainder of 127.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we subtract 621 from 748, we get 127.
Take the next digit (5) from the dividend and append it to 127, then repeat: 1275 / 621

Advancing to step 4:
If we divide 1275 by 621, we get 2 and a remainder of 33.
Record the quotient 2 as the next digit in the result. 
Result so far: 12.0
Subtracting 1242 from 1275 leaves us with 33.
Fetch the next digit (6) from the dividend, attach it to 33 and continue: 336 / 621

On to step 5:
The number 621 fits into 336 0 times, leaving a remainder of 336.
Record the quotient 0 as the next digit in the result. 
Result so far: 120.0
Deduct 0 from 336 and we're left with 336.
Bring next digit (0) of the dividend behind the 336 and repeat the process: 3360 / 621

Let's proceed to step 6:
621 goes into 3360 5 times with a remainder of 255.
The next digit of our result is 5. 
Result so far: 1205.0
Subtracting 3105 from 3360 leaves us with 255.
Include the next digit (9) from the dividend after 255, then repeat: 2559 / 621

Advancing to step 7:
621 goes into 2559 4 times with a remainder of 75.
Record the quotient 4 as the next digit in the result. 
Result so far: 12054.0
If we subtract 2484 from 2559, we get 75.
Include the next digit (9) from the dividend after 75, then repeat: 759 / 621

Let's proceed to step 8:
621 can be fit into 759 1 times, resulting in a remainder of 138.
Put 1 as the next digit of the answer. 
Result so far: 120541.0
The remainder is 138 after subtracting 621 from 759.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1380, and continue the process.

Let's proceed to step 9:
If we divide 1380 by 621, we get 2 and a remainder of 138.
Record the quotient 2 as the next digit in the result. 
Result so far: 120541.2
If we take 1242 away from 1380, we end up with 138.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1380, and continue the process.

Step 10:
The number 621 fits into 1380 2 times, leaving a remainder of 138.
Use 2 as the next digit of our solution. 
Result so far: 120541.22
If we subtract 1242 from 1380, we get 138.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1380, and continue the process.

The quotient of the division is 120541.22, and the remainder is 0.138.