661354 ÷ 12 
Let's see how many times 12 fits into 661354.

Moving on to step 1:
If we divide 6 by 12, we get 0 and a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Grab the next digit (6) from the dividend, add it to 6, then carry on: 66 / 12

Let's proceed to step 2:
12 goes into 66 5 times with a remainder of 6.
The number 5 becomes the next digit in our result. 
Result so far: 5.0
The remainder is 6 after subtracting 60 from 66.
Include the next digit (1) from the dividend after 6, then repeat: 61 / 12

Moving on to step 3:
When dividing 61 by 12, we get 5 with a remainder of 1.
Put 5 as the next digit of the answer. 
Result so far: 55.0
The remainder is 1 after subtracting 60 from 61.
Fetch the next digit (3) from the dividend, attach it to 1 and continue: 13 / 12

Going ahead to step 4:
12 can be fit into 13 1 times, resulting in a remainder of 1.
Put 1 as the next digit of the answer. 
Result so far: 551.0
Subtracting 12 from 13 leaves us with 1.
Grab the next digit (5) from the dividend, add it to 1, then carry on: 15 / 12

On to step 5:
15 divided by 12 is 1 with a remainder of 3.
Write down 1 as next digit of the result. 
Result so far: 5511.0
The remainder is 3 after subtracting 12 from 15.
Append the next digit (4) from the dividend to 3 and continue with: 34 / 12

Let's proceed to step 6:
If we divide 34 by 12, we get 2 and a remainder of 10.
Put 2 as the next digit of the answer. 
Result so far: 55112.0
Deduct 24 from 34 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.

On to step 7:
When dividing 100 by 12, we get 8 with a remainder of 4.
Use 8 as the next digit of our solution. 
Result so far: 55112.8
Subtracting 96 from 100 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.

Step 8:
If we divide 40 by 12, we get 3 and a remainder of 4.
The next digit of our result is 3. 
Result so far: 55112.83
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.

Going ahead to step 9:
40 divided by 12 is 3 with a remainder of 4.
Write down 3 as next digit of the result. 
Result so far: 55112.833
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 55112.833, with a leftover of 0.0004.