210906 ÷ 90 
The aim is to understand the frequency of 90 in 210906.

Step 1:
90 goes into 2 0 times with a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Append the next digit (1) from the dividend to 2 and continue with: 21 / 90

Advancing to step 2:
When dividing 21 by 90, we get 0 with a remainder of 21.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 21 after subtracting 0 from 21.
Grab the next digit (0) from the dividend, add it to 21, then carry on: 210 / 90

On to step 3:
210 divided by 90 is 2 with a remainder of 30.
The next digit of our result is 2. 
Result so far: 2.0
If we take 180 away from 210, we end up with 30.
Grab the next digit (9) from the dividend, add it to 30, then carry on: 309 / 90

On to step 4:
309 divided by 90 is 3 with a remainder of 39.
Write down 3 as next digit of the result. 
Result so far: 23.0
Subtracting 270 from 309 leaves us with 39.
Grab the next digit (0) from the dividend, add it to 39, then carry on: 390 / 90

Step 5:
390 divided by 90 is 4 with a remainder of 30.
Put 4 as the next digit of the answer. 
Result so far: 234.0
Deduct 360 from 390 and we're left with 30.
Append the next digit (6) from the dividend to 30 and continue with: 306 / 90

Moving on to step 6:
The number 90 fits into 306 3 times, leaving a remainder of 36.
Record the quotient 3 as the next digit in the result. 
Result so far: 2343.0
The remainder is 36 after subtracting 270 from 306.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

On to step 7:
90 goes into 360 4 times with a remainder of 0.
The number 4 becomes the next digit in our result. 
Result so far: 2343.4
If we take 360 away from 360, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

On to step 8:
If we divide 0 by 90, we get 0 and a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 2343.4
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 9:
0 divided by 90 is 0 with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 2343.4
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

After the division, we end up with 2343.4 and a remainder of 0.0.