We look at the division of 556426 by 90 
The aim is to understand the frequency of 90 in 556426.

On to step 1:
90 can be fit into 5 0 times, resulting in a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Include the next digit (5) from the dividend after 5, then repeat: 55 / 90

Let's proceed to step 2:
If we divide 55 by 90, we get 0 and a remainder of 55.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 55, we end up with 55.
Append the next digit (6) from the dividend to 55 and continue with: 556 / 90

Step 3:
If we divide 556 by 90, we get 6 and a remainder of 16.
Put 6 as the next digit of the answer. 
Result so far: 6.0
Deduct 540 from 556 and we're left with 16.
Fetch the next digit (4) from the dividend, attach it to 16 and continue: 164 / 90

Let's proceed to step 4:
90 can be fit into 164 1 times, resulting in a remainder of 74.
Use 1 as the next digit of our solution. 
Result so far: 61.0
Subtracting 90 from 164 leaves us with 74.
Fetch the next digit (2) from the dividend, attach it to 74 and continue: 742 / 90

On to step 5:
The number 90 fits into 742 8 times, leaving a remainder of 22.
Put 8 as the next digit of the answer. 
Result so far: 618.0
Deduct 720 from 742 and we're left with 22.
Append the next digit (6) from the dividend to 22 and continue with: 226 / 90

Step 6:
When dividing 226 by 90, we get 2 with a remainder of 46.
Put 2 as the next digit of the answer. 
Result so far: 6182.0
Subtract 180 from 226 to get 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Going ahead to step 7:
90 goes into 460 5 times with a remainder of 10.
Put 5 as the next digit of the answer. 
Result so far: 6182.5
Subtracting 450 from 460 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 8:
The number 90 fits into 100 1 times, leaving a remainder of 10.
Write down 1 as next digit of the result. 
Result so far: 6182.51
If we take 90 away from 100, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

On to step 9:
90 can be fit into 100 1 times, resulting in a remainder of 10.
Put 1 as the next digit of the answer. 
Result so far: 6182.511
Subtracting 90 from 100 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Our division results in 6182.511 with a remaining 0.001.