166139 ÷ 39 
Let's see how many times 39 fits into 166139.

Going ahead to step 1:
When dividing 1 by 39, we get 0 with a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 1 to get 1.
Append the next digit (6) from the dividend to 1 and continue with: 16 / 39

Step 2:
If we divide 16 by 39, we get 0 and a remainder of 16.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 16 after subtracting 0 from 16.
Bring next digit (6) of the dividend behind the 16 and repeat the process: 166 / 39

Step 3:
If we divide 166 by 39, we get 4 and a remainder of 10.
The next digit of our result is 4. 
Result so far: 4.0
Deduct 156 from 166 and we're left with 10.
Bring next digit (1) of the dividend behind the 10 and repeat the process: 101 / 39

Going ahead to step 4:
101 divided by 39 is 2 with a remainder of 23.
Write down 2 as next digit of the result. 
Result so far: 42.0
If we subtract 78 from 101, we get 23.
Take the next digit (3) from the dividend and append it to 23, then repeat: 233 / 39

Step 5:
39 can be fit into 233 5 times, resulting in a remainder of 38.
Put 5 as the next digit of the answer. 
Result so far: 425.0
The remainder is 38 after subtracting 195 from 233.
Take the next digit (9) from the dividend and append it to 38, then repeat: 389 / 39

On to step 6:
39 goes into 389 9 times with a remainder of 38.
The next digit of our result is 9. 
Result so far: 4259.0
Subtract 351 from 389 to get 38.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

Step 7:
When dividing 380 by 39, we get 9 with a remainder of 29.
The number 9 becomes the next digit in our result. 
Result so far: 4259.9
Subtract 351 from 380 to get 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

Let's proceed to step 8:
The number 39 fits into 290 7 times, leaving a remainder of 17.
Use 7 as the next digit of our solution. 
Result so far: 4259.97
If we subtract 273 from 290, we get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

On to step 9:
39 can be fit into 170 4 times, resulting in a remainder of 14.
Put 4 as the next digit of the answer. 
Result so far: 4259.974
If we take 156 away from 170, we end up with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Advancing to step 10:
The number 39 fits into 140 3 times, leaving a remainder of 23.
Put 3 as the next digit of the answer. 
Result so far: 4259.9743
If we take 117 away from 140, we end up with 23.
Since there are no more digits in the dividend, we add a zero to the remainder making it 230, and continue the process.

Let's proceed to step 11:
39 goes into 230 5 times with a remainder of 35.
Record the quotient 5 as the next digit in the result. 
Result so far: 4259.97435
Deduct 195 from 230 and we're left with 35.
Since there are no more digits in the dividend, we add a zero to the remainder making it 350, and continue the process.

Moving on to step 12:
39 goes into 350 8 times with a remainder of 38.
Use 8 as the next digit of our solution. 
Result so far: 4259.974358
Subtracting 312 from 350 leaves us with 38.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

Going ahead to step 13:
If we divide 380 by 39, we get 9 and a remainder of 29.
The number 9 becomes the next digit in our result. 
Result so far: 4259.9743589
If we take 351 away from 380, we end up with 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

Step 14:
If we divide 290 by 39, we get 7 and a remainder of 17.
Write down 7 as next digit of the result. 
Result so far: 4259.97435897
Subtracting 273 from 290 leaves us with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

The final outcome is 4259.97435897, with a leftover of 1.7e-08.