We look at the division of 420790 by 9 
The aim is to understand the frequency of 9 in 420790.

Advancing to step 1:
9 can be fit into 4 0 times, resulting in a remainder of 4.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Take the next digit (2) from the dividend and append it to 4, then repeat: 42 / 9

Moving on to step 2:
If we divide 42 by 9, we get 4 and a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
The remainder is 6 after subtracting 36 from 42.
Fetch the next digit (0) from the dividend, attach it to 6 and continue: 60 / 9

Advancing to step 3:
If we divide 60 by 9, we get 6 and a remainder of 6.
The next digit of our result is 6. 
Result so far: 46.0
The remainder is 6 after subtracting 54 from 60.
Append the next digit (7) from the dividend to 6 and continue with: 67 / 9

Going ahead to step 4:
9 goes into 67 7 times with a remainder of 4.
Write down 7 as next digit of the result. 
Result so far: 467.0
Subtract 63 from 67 to get 4.
Append the next digit (9) from the dividend to 4 and continue with: 49 / 9

Step 5:
49 divided by 9 is 5 with a remainder of 4.
Record the quotient 5 as the next digit in the result. 
Result so far: 4675.0
The remainder is 4 after subtracting 45 from 49.
Grab the next digit (0) from the dividend, add it to 4, then carry on: 40 / 9

Moving on to step 6:
40 divided by 9 is 4 with a remainder of 4.
Put 4 as the next digit of the answer. 
Result so far: 46754.0
Subtracting 36 from 40 leaves us with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 7:
9 goes into 40 4 times with a remainder of 4.
Put 4 as the next digit of the answer. 
Result so far: 46754.4
Subtract 36 from 40 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

On to step 8:
9 can be fit into 40 4 times, resulting in a remainder of 4.
The next digit of our result is 4. 
Result so far: 46754.44
Deduct 36 from 40 and we're left with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The final outcome is 46754.44, with a leftover of 0.004.