We look at the division of 645640 by 90 
We're looking to find how many times 90 goes into 645640.

Advancing to step 1:
If we divide 6 by 90, we get 0 and a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 90

Advancing to step 2:
90 goes into 64 0 times with a remainder of 64.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 64 after subtracting 0 from 64.
Include the next digit (5) from the dividend after 64, then repeat: 645 / 90

Advancing to step 3:
90 can be fit into 645 7 times, resulting in a remainder of 15.
The next digit of our result is 7. 
Result so far: 7.0
Subtracting 630 from 645 leaves us with 15.
Fetch the next digit (6) from the dividend, attach it to 15 and continue: 156 / 90

Let's proceed to step 4:
90 can be fit into 156 1 times, resulting in a remainder of 66.
Record the quotient 1 as the next digit in the result. 
Result so far: 71.0
Deduct 90 from 156 and we're left with 66.
Take the next digit (4) from the dividend and append it to 66, then repeat: 664 / 90

On to step 5:
664 divided by 90 is 7 with a remainder of 34.
Write down 7 as next digit of the result. 
Result so far: 717.0
If we take 630 away from 664, we end up with 34.
Grab the next digit (0) from the dividend, add it to 34, then carry on: 340 / 90

Let's proceed to step 6:
90 can be fit into 340 3 times, resulting in a remainder of 70.
Write down 3 as next digit of the result. 
Result so far: 7173.0
The remainder is 70 after subtracting 270 from 340.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

On to step 7:
The number 90 fits into 700 7 times, leaving a remainder of 70.
Write down 7 as next digit of the result. 
Result so far: 7173.7
Subtracting 630 from 700 leaves us with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

Going ahead to step 8:
90 can be fit into 700 7 times, resulting in a remainder of 70.
Use 7 as the next digit of our solution. 
Result so far: 7173.77
If we take 630 away from 700, we end up with 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 700, and continue the process.

In conclusion, the division gives 7173.77 with a balance of 0.07.