Let's divide 638578 by 12
We're looking to find how many times 12 goes into 638578.

Step 1:
If we divide 6 by 12, we get 0 and a remainder of 6.
Use 0 as the next digit of our solution. 
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

Moving on to step 2:
When dividing 63 by 12, we get 5 with a remainder of 3.
Use 5 as the next digit of our solution. 
Result so far: 5.0
The remainder is 3 after subtracting 60 from 63.
Include the next digit (8) from the dividend after 3, then repeat: 38 / 12

Moving on to step 3:
The number 12 fits into 38 3 times, leaving a remainder of 2.
Use 3 as the next digit of our solution. 
Result so far: 53.0
Deduct 36 from 38 and we're left with 2.
Grab the next digit (5) from the dividend, add it to 2, then carry on: 25 / 12

Going ahead to step 4:
If we divide 25 by 12, we get 2 and a remainder of 1.
Use 2 as the next digit of our solution. 
Result so far: 532.0
If we subtract 24 from 25, we get 1.
Append the next digit (7) from the dividend to 1 and continue with: 17 / 12

Advancing to step 5:
The number 12 fits into 17 1 times, leaving a remainder of 5.
Record the quotient 1 as the next digit in the result. 
Result so far: 5321.0
The remainder is 5 after subtracting 12 from 17.
Include the next digit (8) from the dividend after 5, then repeat: 58 / 12

Let's proceed to step 6:
58 divided by 12 is 4 with a remainder of 10.
The number 4 becomes the next digit in our result. 
Result so far: 53214.0
The remainder is 10 after subtracting 48 from 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 7:
12 can be fit into 100 8 times, resulting in a remainder of 4.
Put 8 as the next digit of the answer. 
Result so far: 53214.8
The remainder is 4 after subtracting 96 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Step 8:
When dividing 40 by 12, we get 3 with a remainder of 4.
The next digit of our result is 3. 
Result so far: 53214.83
Subtracting 36 from 40 leaves us 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 9:
If we divide 40 by 12, we get 3 and a remainder of 4.
Write down 3 as next digit of the result. 
Result so far: 53214.833
Deduct 36 from 40 and we're left 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.

The final result is 53214.833 with a remainder of 0.0004.