We look at the division of 66409959 by 166 
Our goal is to divide 66409959 by 166.

Advancing to step 1:
166 goes into 6 0 times with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Fetch the next digit (6) from the dividend, attach it to 6 and continue: 66 / 166

Going ahead to step 2:
When dividing 66 by 166, we get 0 with a remainder of 66.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 66 after subtracting 0 from 66.
Append the next digit (4) from the dividend to 66 and continue with: 664 / 166

Step 3:
664 divided by 166 is 4 with a remainder of 0.
Use 4 as the next digit of our solution. 
Result so far: 4.0
The remainder is 0 after subtracting 664 from 664.
Bring next digit (0) of the dividend behind the 0 and repeat the process: 0 / 166

Advancing to step 4:
0 divided by 166 is 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 40.0
Subtract 0 from 0 to get 0.
Grab the next digit (9) from the dividend, add it to 0, then carry on: 9 / 166

Advancing to step 5:
166 goes into 9 0 times with a remainder of 9.
Write down 0 as next digit of the result. 
Result so far: 400.0
Deduct 0 from 9 and we're left with 9.
Take the next digit (9) from the dividend and append it to 9, then repeat: 99 / 166

Moving on to step 6:
99 divided by 166 is 0 with a remainder of 99.
Use 0 as the next digit of our solution. 
Result so far: 4000.0
Subtract 0 from 99 to get 99.
Take the next digit (5) from the dividend and append it to 99, then repeat: 995 / 166

On to step 7:
If we divide 995 by 166, we get 5 and a remainder of 165.
Put 5 as the next digit of the answer. 
Result so far: 40005.0
If we subtract 830 from 995, we get 165.
Take the next digit (9) from the dividend and append it to 165, then repeat: 1659 / 166

Going ahead to step 8:
166 can be fit into 1659 9 times, resulting in a remainder of 165.
The next digit of our result is 9. 
Result so far: 400059.0
The remainder is 165 after subtracting 1494 from 1659.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1650, and continue the process.

On to step 9:
1650 divided by 166 is 9 with a remainder of 156.
Write down 9 as next digit of the result. 
Result so far: 400059.9
If we subtract 1494 from 1650, we get 156.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1560, and continue the process.

Let's proceed to step 10:
When dividing 1560 by 166, we get 9 with a remainder of 66.
The next digit of our result is 9. 
Result so far: 400059.99
If we subtract 1494 from 1560, we get 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

After the division, we end up with 400059.99 and a remainder of 0.066.