We divide 603991 by 90
Our goal is to divide 603991 by 90.

Going ahead to step 1:
6 divided by 90 is 0 with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Include the next digit (0) from the dividend after 6, then repeat: 60 / 90

On to step 2:
60 divided by 90 is 0 with a remainder of 60.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 60, we end up with 60.
Grab the next digit (3) from the dividend, add it to 60, then carry on: 603 / 90

Going ahead to step 3:
If we divide 603 by 90, we get 6 and a remainder of 63.
The number 6 becomes the next digit in our result. 
Result so far: 6.0
If we take 540 away from 603, we end up with 63.
Append the next digit (9) from the dividend to 63 and continue with: 639 / 90

Moving on to step 4:
If we divide 639 by 90, we get 7 and a remainder of 9.
The next digit of our result is 7. 
Result so far: 67.0
Deduct 630 from 639 and we're left with 9.
Grab the next digit (9) from the dividend, add it to 9, then carry on: 99 / 90

Advancing to step 5:
90 can be fit into 99 1 times, resulting in a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 671.0
If we take 90 away from 99, we end up with 9.
Grab the next digit (1) from the dividend, add it to 9, then carry on: 91 / 90

Going ahead to step 6:
91 divided by 90 is 1 with a remainder of 1.
The next digit of our result is 1. 
Result so far: 6711.0
The remainder is 1 after subtracting 90 from 91.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Moving on to step 7:
10 divided by 90 is 0 with a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 6711.0
Subtract 0 from 10 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 8:
If we divide 100 by 90, we get 1 and a remainder of 10.
Use 1 as the next digit of our solution. 
Result so far: 6711.01
The remainder is 10 after subtracting 90 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 9:
The number 90 fits into 100 1 times, leaving a remainder of 10.
Put 1 as the next digit of the answer. 
Result so far: 6711.011
Subtract 90 from 100 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

In conclusion, the division gives 6711.011 with a balance of 0.001.