We look at the division of 342391 by 86 
We want to figure out the number of times 342391 can be divided by 86.

Moving on to step 1:
The number 86 fits into 3 0 times, leaving a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Grab the next digit (4) from the dividend, add it to 3, then carry on: 34 / 86

Advancing to step 2:
34 divided by 86 is 0 with a remainder of 34.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 34 to get 34.
Append the next digit (2) from the dividend to 34 and continue with: 342 / 86

On to step 3:
If we divide 342 by 86, we get 3 and a remainder of 84.
Use 3 as the next digit of our solution. 
Result so far: 3.0
Subtracting 258 from 342 leaves us with 84.
Fetch the next digit (3) from the dividend, attach it to 84 and continue: 843 / 86

Advancing to step 4:
The number 86 fits into 843 9 times, leaving a remainder of 69.
Use 9 as the next digit of our solution. 
Result so far: 39.0
If we take 774 away from 843, we end up with 69.
Append the next digit (9) from the dividend to 69 and continue with: 699 / 86

Advancing to step 5:
86 goes into 699 8 times with a remainder of 11.
Put 8 as the next digit of the answer. 
Result so far: 398.0
Deduct 688 from 699 and we're left with 11.
Grab the next digit (1) from the dividend, add it to 11, then carry on: 111 / 86

Let's proceed to step 6:
111 divided by 86 is 1 with a remainder of 25.
Record the quotient 1 as the next digit in the result. 
Result so far: 3981.0
If we take 86 away from 111, we end up with 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

On to step 7:
86 goes into 250 2 times with a remainder of 78.
The number 2 becomes the next digit in our result. 
Result so far: 3981.2
Subtracting 172 from 250 leaves us with 78.
Since there are no more digits in the dividend, we add a zero to the remainder making it 780, and continue the process.

Step 8:
780 divided by 86 is 9 with a remainder of 6.
Record the quotient 9 as the next digit in the result. 
Result so far: 3981.29
If we take 774 away from 780, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 9:
86 can be fit into 60 0 times, resulting in a remainder of 60.
The next digit of our result is 0. 
Result so far: 3981.29
Subtracting 0 from 60 leaves us with 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Let's proceed to step 10:
86 can be fit into 600 6 times, resulting in a remainder of 84.
Use 6 as the next digit of our solution. 
Result so far: 3981.2906
The remainder is 84 after subtracting 516 from 600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 840, and continue the process.

On to step 11:
840 divided by 86 is 9 with a remainder of 66.
Put 9 as the next digit of the answer. 
Result so far: 3981.29069
The remainder is 66 after subtracting 774 from 840.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Step 12:
If we divide 660 by 86, we get 7 and a remainder of 58.
The next digit of our result is 7. 
Result so far: 3981.290697
Deduct 602 from 660 and we're left with 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

On to step 13:
86 can be fit into 580 6 times, resulting in a remainder of 64.
The number 6 becomes the next digit in our result. 
Result so far: 3981.2906976
The remainder is 64 after subtracting 516 from 580.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

Moving on to step 14:
When dividing 640 by 86, we get 7 with a remainder of 38.
Use 7 as the next digit of our solution. 
Result so far: 3981.29069767
If we take 602 away from 640, we end up 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.

The final outcome is 3981.29069767, with a leftover of 3.8e-08.