166640 ÷ 90 
The aim is to understand the frequency of 90 in 166640.

Let's proceed to step 1:
90 goes into 1 0 times with a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Append the next digit (6) from the dividend to 1 and continue with: 16 / 90

Let's proceed to step 2:
16 divided by 90 is 0 with a remainder of 16.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 16 leaves us with 16.
Bring next digit (6) of the dividend behind the 16 and repeat the process: 166 / 90

Step 3:
90 goes into 166 1 times with a remainder of 76.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
If we take 90 away from 166, we end up with 76.
Bring next digit (6) of the dividend behind the 76 and repeat the process: 766 / 90

Going ahead to step 4:
When dividing 766 by 90, we get 8 with a remainder of 46.
Record the quotient 8 as the next digit in the result. 
Result so far: 18.0
Subtracting 720 from 766 leaves us with 46.
Fetch the next digit (4) from the dividend, attach it to 46 and continue: 464 / 90

Advancing to step 5:
464 divided by 90 is 5 with a remainder of 14.
Write down 5 as next digit of the result. 
Result so far: 185.0
Deduct 450 from 464 and we're left with 14.
Bring next digit (0) of the dividend behind the 14 and repeat the process: 140 / 90

Let's proceed to step 6:
140 divided by 90 is 1 with a remainder of 50.
Put 1 as the next digit of the answer. 
Result so far: 1851.0
Subtract 90 from 140 to get 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Let's proceed to step 7:
90 can be fit into 500 5 times, resulting in a remainder of 50.
Write down 5 as next digit of the result. 
Result so far: 1851.5
Deduct 450 from 500 and we're left with 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Let's proceed to step 8:
90 can be fit into 500 5 times, resulting in a remainder of 50.
Write down 5 as next digit of the result. 
Result so far: 1851.55
If we take 450 away from 500, we end up with 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

The final result is 1851.55 with a remainder of 0.05.