640494 divided by 20 
Let's see how many times 20 fits into 640494.

Advancing to step 1:
The number 20 fits into 6 0 times, leaving a remainder of 6.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 20

On to step 2:
20 goes into 64 3 times with a remainder of 4.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
Subtract 60 from 64 to get 4.
Append the next digit (0) from the dividend to 4 and continue with: 40 / 20

Advancing to step 3:
40 divided by 20 is 2 with a remainder of 0.
Write down 2 as next digit of the result. 
Result so far: 32.0
Subtracting 40 from 40 leaves us with 0.
Take the next digit (4) from the dividend and append it to 0, then repeat: 4 / 20

Advancing to step 4:
4 divided by 20 is 0 with a remainder of 4.
Use 0 as the next digit of our solution. 
Result so far: 320.0
Subtracting 0 from 4 leaves us with 4.
Bring next digit (9) of the dividend behind the 4 and repeat the process: 49 / 20

Let's proceed to step 5:
The number 20 fits into 49 2 times, leaving a remainder of 9.
The number 2 becomes the next digit in our result. 
Result so far: 3202.0
If we subtract 40 from 49, we get 9.
Append the next digit (4) from the dividend to 9 and continue with: 94 / 20

Moving on to step 6:
The number 20 fits into 94 4 times, leaving a remainder of 14.
Record the quotient 4 as the next digit in the result. 
Result so far: 32024.0
Subtract 80 from 94 to get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Moving on to step 7:
20 goes into 140 7 times with a remainder of 0.
Put 7 as the next digit of the answer. 
Result so far: 32024.7
If we subtract 140 from 140, 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:
The number 20 fits into 0 0 times, leaving a remainder of 0.
The next digit of our result is 0. 
Result so far: 32024.7
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.

Going ahead to step 9:
If we divide 0 by 20, we get 0 and a remainder of 0.
The next digit of our result is 0. 
Result so far: 32024.7
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 32024.7 and a remainder of 0.0.