Let's divide 840649 by 90
The aim is to understand the frequency of 90 in 840649.

On to step 1:
The number 90 fits into 8 0 times, leaving a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 8 to get 8.
Include the next digit (4) from the dividend after 8, then repeat: 84 / 90

Moving on to step 2:
When dividing 84 by 90, we get 0 with a remainder of 84.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 84, we end up with 84.
Include the next digit (0) from the dividend after 84, then repeat: 840 / 90

Let's proceed to step 3:
90 can be fit into 840 9 times, resulting in a remainder of 30.
Use 9 as the next digit of our solution. 
Result so far: 9.0
If we subtract 810 from 840, we get 30.
Bring next digit (6) of the dividend behind the 30 and repeat the process: 306 / 90

Step 4:
When dividing 306 by 90, we get 3 with a remainder of 36.
Use 3 as the next digit of our solution. 
Result so far: 93.0
The remainder is 36 after subtracting 270 from 306.
Grab the next digit (4) from the dividend, add it to 36, then carry on: 364 / 90

Moving on to step 5:
90 goes into 364 4 times with a remainder of 4.
The next digit of our result is 4. 
Result so far: 934.0
The remainder is 4 after subtracting 360 from 364.
Fetch the next digit (9) from the dividend, attach it to 4 and continue: 49 / 90

Going ahead to step 6:
49 divided by 90 is 0 with a remainder of 49.
The number 0 becomes the next digit in our result. 
Result so far: 9340.0
Subtract 0 from 49 to get 49.
Since there are no more digits in the dividend, we add a zero to the remainder making it 490, and continue the process.

On to step 7:
90 goes into 490 5 times with a remainder of 40.
Write down 5 as next digit of the result. 
Result so far: 9340.5
Subtracting 450 from 490 leaves us with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Step 8:
90 can be fit into 400 4 times, resulting in a remainder of 40.
The next digit of our result is 4. 
Result so far: 9340.54
Deduct 360 from 400 and we're left with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Advancing to step 9:
The number 90 fits into 400 4 times, leaving a remainder of 40.
The number 4 becomes the next digit in our result. 
Result so far: 9340.544
Deduct 360 from 400 and we're left with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

The final outcome is 9340.544, with a leftover of 0.004.