We look at the division of 213846 by 90 
The aim is to understand the frequency of 90 in 213846.

Step 1:
If we divide 2 by 90, we get 0 and a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 2 after subtracting 0 from 2.
Append the next digit (1) from the dividend to 2 and continue with: 21 / 90

Step 2:
90 can be fit into 21 0 times, resulting in a remainder of 21.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 21, we end up with 21.
Include the next digit (3) from the dividend after 21, then repeat: 213 / 90

On to step 3:
The number 90 fits into 213 2 times, leaving a remainder of 33.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
If we take 180 away from 213, we end up with 33.
Grab the next digit (8) from the dividend, add it to 33, then carry on: 338 / 90

On to step 4:
If we divide 338 by 90, we get 3 and a remainder of 68.
Use 3 as the next digit of our solution. 
Result so far: 23.0
Deduct 270 from 338 and we're left with 68.
Append the next digit (4) from the dividend to 68 and continue with: 684 / 90

Advancing to step 5:
If we divide 684 by 90, we get 7 and a remainder of 54.
Use 7 as the next digit of our solution. 
Result so far: 237.0
Deduct 630 from 684 and we're left with 54.
Grab the next digit (6) from the dividend, add it to 54, then carry on: 546 / 90

Going ahead to step 6:
If we divide 546 by 90, we get 6 and a remainder of 6.
Put 6 as the next digit of the answer. 
Result so far: 2376.0
Subtract 540 from 546 to get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Advancing to step 7:
60 divided by 90 is 0 with a remainder of 60.
Put 0 as the next digit of the answer. 
Result so far: 2376.0
Deduct 0 from 60 and we're left with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Advancing to step 8:
600 divided by 90 is 6 with a remainder of 60.
Use 6 as the next digit of our solution. 
Result so far: 2376.06
Subtracting 540 from 600 leaves us with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Moving on to step 9:
90 goes into 600 6 times with a remainder of 60.
Use 6 as the next digit of our solution. 
Result so far: 2376.066
If we take 540 away from 600, we end up with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

The final outcome is 2376.066, with a leftover of 0.006.