We're dividing 258639 by 85 
We're looking to find how many times 85 goes into 258639.

Step 1:
85 goes into 2 0 times with a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 2, we end up with 2.
Fetch the next digit (5) from the dividend, attach it to 2 and continue: 25 / 85

Moving on to step 2:
The number 85 fits into 25 0 times, leaving a remainder of 25.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 25 leaves us with 25.
Take the next digit (8) from the dividend and append it to 25, then repeat: 258 / 85

Moving on to step 3:
258 divided by 85 is 3 with a remainder of 3.
Write down 3 as next digit of the result. 
Result so far: 3.0
If we subtract 255 from 258, we get 3.
Grab the next digit (6) from the dividend, add it to 3, then carry on: 36 / 85

Advancing to step 4:
85 can be fit into 36 0 times, resulting in a remainder of 36.
Record the quotient 0 as the next digit in the result. 
Result so far: 30.0
The remainder is 36 after subtracting 0 from 36.
Take the next digit (3) from the dividend and append it to 36, then repeat: 363 / 85

Going ahead to step 5:
85 can be fit into 363 4 times, resulting in a remainder of 23.
Put 4 as the next digit of the answer. 
Result so far: 304.0
Subtract 340 from 363 to get 23.
Include the next digit (9) from the dividend after 23, then repeat: 239 / 85

Let's proceed to step 6:
85 can be fit into 239 2 times, resulting in a remainder of 69.
Record the quotient 2 as the next digit in the result. 
Result so far: 3042.0
If we take 170 away from 239, we end up with 69.
Since there are no more digits in the dividend, we add a zero to the remainder making it 690, and continue the process.

Let's proceed to step 7:
690 divided by 85 is 8 with a remainder of 10.
The next digit of our result is 8. 
Result so far: 3042.8
Deduct 680 from 690 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.

Moving on to step 8:
100 divided by 85 is 1 with a remainder of 15.
Write down 1 as next digit of the result. 
Result so far: 3042.81
Subtracting 85 from 100 leaves us with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Going ahead to step 9:
If we divide 150 by 85, we get 1 and a remainder of 65.
The next digit of our result is 1. 
Result so far: 3042.811
The remainder is 65 after subtracting 85 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 650, and continue the process.

Our division results in 3042.811 with a remaining 0.0065.