We're dividing 15065989 by 858 
Our goal is to divide 15065989 by 858.

Step 1:
If we divide 1 by 858, we get 0 and a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Take the next digit (5) from the dividend and append it to 1, then repeat: 15 / 858

Step 2:
If we divide 15 by 858, we get 0 and a remainder of 15.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 15 and we're left with 15.
Grab the next digit (0) from the dividend, add it to 15, then carry on: 150 / 858

Moving on to step 3:
858 can be fit into 150 0 times, resulting in a remainder of 150.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 150 leaves us with 150.
Append the next digit (6) from the dividend to 150 and continue with: 1506 / 858

Advancing to step 4:
858 goes into 1506 1 times with a remainder of 648.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we subtract 858 from 1506, we get 648.
Take the next digit (5) from the dividend and append it to 648, then repeat: 6485 / 858

On to step 5:
858 can be fit into 6485 7 times, resulting in a remainder of 479.
Use 7 as the next digit of our solution. 
Result so far: 17.0
If we take 6006 away from 6485, we end up with 479.
Take the next digit (9) from the dividend and append it to 479, then repeat: 4799 / 858

On to step 6:
858 can be fit into 4799 5 times, resulting in a remainder of 509.
Write down 5 as next digit of the result. 
Result so far: 175.0
Deduct 4290 from 4799 and we're left with 509.
Append the next digit (8) from the dividend to 509 and continue with: 5098 / 858

Advancing to step 7:
858 goes into 5098 5 times with a remainder of 808.
Put 5 as the next digit of the answer. 
Result so far: 1755.0
If we subtract 4290 from 5098, we get 808.
Grab the next digit (9) from the dividend, add it to 808, then carry on: 8089 / 858

Step 8:
When dividing 8089 by 858, we get 9 with a remainder of 367.
The next digit of our result is 9. 
Result so far: 17559.0
Subtracting 7722 from 8089 leaves us with 367.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3670, and continue the process.

Going ahead to step 9:
3670 divided by 858 is 4 with a remainder of 238.
The number 4 becomes the next digit in our result. 
Result so far: 17559.4
Subtract 3432 from 3670 to get 238.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2380, and continue the process.

Moving on to step 10:
The number 858 fits into 2380 2 times, leaving a remainder of 664.
Record the quotient 2 as the next digit in the result. 
Result so far: 17559.42
Deduct 1716 from 2380 and we're left with 664.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6640, and continue the process.

Let's proceed to step 11:
858 can be fit into 6640 7 times, resulting in a remainder of 634.
Write down 7 as next digit of the result. 
Result so far: 17559.427
The remainder is 634 after subtracting 6006 from 6640.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6340, and continue the process.

Step 12:
When dividing 6340 by 858, we get 7 with a remainder of 334.
Put 7 as the next digit of the answer. 
Result so far: 17559.4277
If we subtract 6006 from 6340, we get 334.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3340, and continue the process.

The final outcome is 17559.4277, with a leftover of 0.00334.