We look at the division of 639766 by 12 
We're looking to find how many times 12 goes into 639766.

Step 1:
If we divide 6 by 12, we get 0 and a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Include the next digit (3) from the dividend after 6, then repeat: 63 / 12

Going ahead to step 2:
If we divide 63 by 12, we get 5 and a remainder of 3.
Put 5 as the next digit of the answer. 
Result so far: 5.0
If we subtract 60 from 63, we get 3.
Fetch the next digit (9) from the dividend, attach it to 3 and continue: 39 / 12

Step 3:
12 goes into 39 3 times with a remainder of 3.
The next digit of our result is 3. 
Result so far: 53.0
The remainder is 3 after subtracting 36 from 39.
Grab the next digit (7) from the dividend, add it to 3, then carry on: 37 / 12

Moving on to step 4:
If we divide 37 by 12, we get 3 and a remainder of 1.
Record the quotient 3 as the next digit in the result. 
Result so far: 533.0
Deduct 36 from 37 and we're left with 1.
Grab the next digit (6) from the dividend, add it to 1, then carry on: 16 / 12

Advancing to step 5:
16 divided by 12 is 1 with a remainder of 4.
Write down 1 as next digit of the result. 
Result so far: 5331.0
The remainder is 4 after subtracting 12 from 16.
Bring next digit (6) of the dividend behind the 4 and repeat the process: 46 / 12

Step 6:
If we divide 46 by 12, we get 3 and a remainder of 10.
Put 3 as the next digit of the answer. 
Result so far: 53313.0
Subtract 36 from 46 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 7:
If we divide 100 by 12, we get 8 and a remainder of 4.
Write down 8 as next digit of the result. 
Result so far: 53313.8
If we take 96 away from 100, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 8:
If we divide 40 by 12, we get 3 and a remainder of 4.
The number 3 becomes the next digit in our result. 
Result so far: 53313.83
The remainder is 4 after subtracting 36 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Step 9:
12 can be fit into 40 3 times, resulting in a remainder of 4.
Write down 3 as next digit of the result. 
Result so far: 53313.833
If we subtract 36 from 40, we get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

The final outcome is 53313.833, with a leftover of 0.0004.