We look at the division of 643705 by 20 
We're looking to find how many times 20 goes into 643705.

Let's proceed to step 1:
If we divide 6 by 20, we get 0 and a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 6, we end up with 6.
Grab the next digit (4) from the dividend, add it to 6, then carry on: 64 / 20

Advancing 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
The remainder is 4 after subtracting 60 from 64.
Take the next digit (3) from the dividend and append it to 4, then repeat: 43 / 20

Moving on to step 3:
When dividing 43 by 20, we get 2 with a remainder of 3.
The number 2 becomes the next digit in our result. 
Result so far: 32.0
The remainder is 3 after subtracting 40 from 43.
Append the next digit (7) from the dividend to 3 and continue with: 37 / 20

Advancing to step 4:
If we divide 37 by 20, we get 1 and a remainder of 17.
Write down 1 as next digit of the result. 
Result so far: 321.0
Subtract 20 from 37 to get 17.
Append the next digit (0) from the dividend to 17 and continue with: 170 / 20

Let's proceed to step 5:
20 can be fit into 170 8 times, resulting in a remainder of 10.
Put 8 as the next digit of the answer. 
Result so far: 3218.0
If we subtract 160 from 170, we get 10.
Append the next digit (5) from the dividend to 10 and continue with: 105 / 20

Moving on to step 6:
The number 20 fits into 105 5 times, leaving a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 32185.0
The remainder is 5 after subtracting 100 from 105.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Step 7:
20 goes into 50 2 times with a remainder of 10.
The next digit of our result is 2. 
Result so far: 32185.2
Deduct 40 from 50 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 8:
20 goes into 100 5 times with a remainder of 0.
Write down 5 as next digit of the result. 
Result so far: 32185.25
The remainder is 0 after subtracting 100 from 100.
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:
When dividing 0 by 20, we get 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 32185.25
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 10:
The number 20 fits into 0 0 times, leaving a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 32185.25
The remainder is 0 after subtracting 0 from 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 32185.25 with a remainder of 0.0.