We look at the division of 639580 by 20 
We want to divide 639580 by 20.

On to step 1:
20 goes into 6 0 times with a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Append the next digit (3) from the dividend to 6 and continue with: 63 / 20

On to step 2:
63 divided by 20 is 3 with a remainder of 3.
Put 3 as the next digit of the answer. 
Result so far: 3.0
If we subtract 60 from 63, we get 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 20

Step 3:
If we divide 39 by 20, we get 1 and a remainder of 19.
The next digit of our result is 1. 
Result so far: 31.0
The remainder is 19 after subtracting 20 from 39.
Grab the next digit (5) from the dividend, add it to 19, then carry on: 195 / 20

Moving on to step 4:
When dividing 195 by 20, we get 9 with a remainder of 15.
Put 9 as the next digit of the answer. 
Result so far: 319.0
Deduct 180 from 195 and we're left with 15.
Include the next digit (8) from the dividend after 15, then repeat: 158 / 20

Advancing to step 5:
When dividing 158 by 20, we get 7 with a remainder of 18.
Write down 7 as next digit of the result. 
Result so far: 3197.0
Deduct 140 from 158 and we're left with 18.
Take the next digit (0) from the dividend and append it to 18, then repeat: 180 / 20

Advancing to step 6:
When dividing 180 by 20, we get 9 with a remainder of 0.
The number 9 becomes the next digit in our result. 
Result so far: 31979.0
Deduct 180 from 180 and we're left with 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 7:
When dividing 0 by 20, we get 0 with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 31979.0
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.

Going ahead to step 8:
If we divide 0 by 20, we get 0 and a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 31979.0
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final result is 31979.0 with a remainder of 0.0.