643868 ÷ 12 
We want to figure out the number of times 643868 can be divided by 12.

On to step 1:
12 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
Subtract 0 from 6 to get 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 12

Step 2:
12 can be fit into 64 5 times, resulting in a remainder of 4.
The number 5 becomes the next digit in our result. 
Result so far: 5.0
If we subtract 60 from 64, we get 4.
Grab the next digit (3) from the dividend, add it to 4, then carry on: 43 / 12

Going ahead to step 3:
12 goes into 43 3 times with a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 53.0
Subtracting 36 from 43 leaves us with 7.
Bring next digit (8) of the dividend behind the 7 and repeat the process: 78 / 12

Moving on to step 4:
If we divide 78 by 12, we get 6 and a remainder of 6.
The next digit of our result is 6. 
Result so far: 536.0
Subtract 72 from 78 to get 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 12

Going ahead to step 5:
12 goes into 66 5 times with a remainder of 6.
The number 5 becomes the next digit in our result. 
Result so far: 5365.0
If we subtract 60 from 66, we get 6.
Bring next digit (8) of the dividend behind the 6 and repeat the process: 68 / 12

Let's proceed to step 6:
68 divided by 12 is 5 with a remainder of 8.
The next digit of our result is 5. 
Result so far: 53655.0
If we subtract 60 from 68, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

On to step 7:
When dividing 80 by 12, we get 6 with a remainder of 8.
Write down 6 as next digit of the result. 
Result so far: 53655.6
Subtract 72 from 80 to get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Step 8:
80 divided by 12 is 6 with a remainder of 8.
Use 6 as the next digit of our solution. 
Result so far: 53655.66
If we take 72 away from 80, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

The final result is 53655.66 with a remainder of 0.008.