12228588 ÷ 858 
We want to figure out the number of times 12228588 can be divided by 858.

Going ahead to step 1:
858 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Take the next digit (2) from the dividend and append it to 1, then repeat: 12 / 858

Moving on to step 2:
The number 858 fits into 12 0 times, leaving a remainder of 12.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 12 leaves us with 12.
Fetch the next digit (2) from the dividend, attach it to 12 and continue: 122 / 858

Moving on to step 3:
858 goes into 122 0 times with a remainder of 122.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 122 leaves us with 122.
Bring next digit (2) of the dividend behind the 122 and repeat the process: 1222 / 858

Going ahead to step 4:
When dividing 1222 by 858, we get 1 with a remainder of 364.
Use 1 as the next digit of our solution. 
Result so far: 1.0
If we subtract 858 from 1222, we get 364.
Take the next digit (8) from the dividend and append it to 364, then repeat: 3648 / 858

Step 5:
The number 858 fits into 3648 4 times, leaving a remainder of 216.
Record the quotient 4 as the next digit in the result. 
Result so far: 14.0
If we subtract 3432 from 3648, we get 216.
Include the next digit (5) from the dividend after 216, then repeat: 2165 / 858

Step 6:
858 can be fit into 2165 2 times, resulting in a remainder of 449.
The number 2 becomes the next digit in our result. 
Result so far: 142.0
If we subtract 1716 from 2165, we get 449.
Append the next digit (8) from the dividend to 449 and continue with: 4498 / 858

Step 7:
The number 858 fits into 4498 5 times, leaving a remainder of 208.
Record the quotient 5 as the next digit in the result. 
Result so far: 1425.0
Deduct 4290 from 4498 and we're left with 208.
Bring next digit (8) of the dividend behind the 208 and repeat the process: 2088 / 858

Moving on to step 8:
When dividing 2088 by 858, we get 2 with a remainder of 372.
Write down 2 as next digit of the result. 
Result so far: 14252.0
The remainder is 372 after subtracting 1716 from 2088.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3720, and continue the process.

On to step 9:
3720 divided by 858 is 4 with a remainder of 288.
The number 4 becomes the next digit in our result. 
Result so far: 14252.4
If we take 3432 away from 3720, we end up with 288.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2880, and continue the process.

Going ahead to step 10:
2880 divided by 858 is 3 with a remainder of 306.
Record the quotient 3 as the next digit in the result. 
Result so far: 14252.43
Subtract 2574 from 2880 to get 306.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3060, and continue the process.

Moving on to step 11:
858 goes into 3060 3 times with a remainder of 486.
Write down 3 as next digit of the result. 
Result so far: 14252.433
If we subtract 2574 from 3060, we get 486.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4860, and continue the process.

The final outcome is 14252.433, with a leftover of 0.0486.