We divide 640521 by 90
Our goal is to divide 640521 by 90.

Going ahead to step 1:
When dividing 6 by 90, we get 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 90

Going ahead to step 2:
90 can be fit into 64 0 times, resulting in a remainder of 64.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 64 leaves us with 64.
Take the next digit (0) from the dividend and append it to 64, then repeat: 640 / 90

Let's proceed to step 3:
90 can be fit into 640 7 times, resulting in a remainder of 10.
The number 7 becomes the next digit in our result. 
Result so far: 7.0
The remainder is 10 after subtracting 630 from 640.
Include the next digit (5) from the dividend after 10, then repeat: 105 / 90

Step 4:
The number 90 fits into 105 1 times, leaving a remainder of 15.
The next digit of our result is 1. 
Result so far: 71.0
If we subtract 90 from 105, we get 15.
Append the next digit (2) from the dividend to 15 and continue with: 152 / 90

Going ahead to step 5:
If we divide 152 by 90, we get 1 and a remainder of 62.
Write down 1 as next digit of the result. 
Result so far: 711.0
Subtracting 90 from 152 leaves us with 62.
Append the next digit (1) from the dividend to 62 and continue with: 621 / 90

On to step 6:
621 divided by 90 is 6 with a remainder of 81.
The number 6 becomes the next digit in our result. 
Result so far: 7116.0
Subtracting 540 from 621 leaves us with 81.
Since there are no more digits in the dividend, we add a zero to the remainder making it 810, and continue the process.

Going ahead to step 7:
The number 90 fits into 810 9 times, leaving a remainder of 0.
The next digit of our result is 9. 
Result so far: 7116.9
If we subtract 810 from 810, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 8:
90 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 7116.9
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Let's proceed to step 9:
90 can be fit into 0 0 times, resulting in a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 7116.9
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

After the division, we end up with 7116.9 and a remainder of 0.0.