We look at the division of 90741621 by 531 
The aim is to understand the frequency of 531 in 90741621.

Advancing to step 1:
531 can be fit into 9 0 times, resulting in a remainder of 9.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 9 leaves us with 9.
Fetch the next digit (0) from the dividend, attach it to 9 and continue: 90 / 531

Advancing to step 2:
531 goes into 90 0 times with a remainder of 90.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 90 after subtracting 0 from 90.
Include the next digit (7) from the dividend after 90, then repeat: 907 / 531

Advancing to step 3:
907 divided by 531 is 1 with a remainder of 376.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Deduct 531 from 907 and we're left with 376.
Append the next digit (4) from the dividend to 376 and continue with: 3764 / 531

Moving on to step 4:
The number 531 fits into 3764 7 times, leaving a remainder of 47.
Put 7 as the next digit of the answer. 
Result so far: 17.0
The remainder is 47 after subtracting 3717 from 3764.
Fetch the next digit (1) from the dividend, attach it to 47 and continue: 471 / 531

On to step 5:
531 can be fit into 471 0 times, resulting in a remainder of 471.
The number 0 becomes the next digit in our result. 
Result so far: 170.0
The remainder is 471 after subtracting 0 from 471.
Include the next digit (6) from the dividend after 471, then repeat: 4716 / 531

On to step 6:
531 goes into 4716 8 times with a remainder of 468.
The next digit of our result is 8. 
Result so far: 1708.0
The remainder is 468 after subtracting 4248 from 4716.
Grab the next digit (2) from the dividend, add it to 468, then carry on: 4682 / 531

On to step 7:
531 goes into 4682 8 times with a remainder of 434.
Put 8 as the next digit of the answer. 
Result so far: 17088.0
Subtracting 4248 from 4682 leaves us with 434.
Grab the next digit (1) from the dividend, add it to 434, then carry on: 4341 / 531

Step 8:
When dividing 4341 by 531, we get 8 with a remainder of 93.
Record the quotient 8 as the next digit in the result. 
Result so far: 170888.0
The remainder is 93 after subtracting 4248 from 4341.
Since there are no more digits in the dividend, we add a zero to the remainder making it 930, and continue the process.

On to step 9:
If we divide 930 by 531, we get 1 and a remainder of 399.
Use 1 as the next digit of our solution. 
Result so far: 170888.1
Subtracting 531 from 930 leaves us with 399.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3990, and continue the process.

Let's proceed to step 10:
The number 531 fits into 3990 7 times, leaving a remainder of 273.
The number 7 becomes the next digit in our result. 
Result so far: 170888.17
Deduct 3717 from 3990 and we're left with 273.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2730, and continue the process.

Advancing to step 11:
531 goes into 2730 5 times with a remainder of 75.
Put 5 as the next digit of the answer. 
Result so far: 170888.175
If we take 2655 away from 2730, we end up with 75.
Since there are no more digits in the dividend, we add a zero to the remainder making it 750, and continue the process.

Advancing to step 12:
When dividing 750 by 531, we get 1 with a remainder of 219.
The number 1 becomes the next digit in our result. 
Result so far: 170888.1751
The remainder is 219 after subtracting 531 from 750.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2190, and continue the process.

Moving on to step 13:
When dividing 2190 by 531, we get 4 with a remainder of 66.
Write down 4 as next digit of the result. 
Result so far: 170888.17514
The remainder is 66 after subtracting 2124 from 2190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Moving on to step 14:
When dividing 660 by 531, we get 1 with a remainder of 129.
The number 1 becomes the next digit in our result. 
Result so far: 170888.175141
Subtracting 531 from 660 leaves us with 129.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1290, and continue the process.

Moving on to step 15:
1290 divided by 531 is 2 with a remainder of 228.
Use 2 as the next digit of our solution. 
Result so far: 170888.1751412
If we subtract 1062 from 1290, we get 228.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2280, and continue the process.

Going ahead to step 16:
2280 divided by 531 is 4 with a remainder of 156.
The next digit of our result is 4. 
Result so far: 170888.17514124
Deduct 2124 from 2280 and we're left with 156.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1560, and continue the process.

Our division results in 170888.17514124 with a remaining 1.56e-07.