86399889 ÷ 1 
We want to figure out the number of times 86399889 can be divided by 1.

Step 1:
The number 1 fits into 8 8 times, leaving a remainder of 0.
The number 8 becomes the next digit in our result. 
Result so far: 8.0
Subtracting 8 from 8 leaves us with 0.
Take the next digit (6) from the dividend and append it to 0, then repeat: 6 / 1

Advancing to step 2:
1 goes into 6 6 times with a remainder of 0.
The next digit of our result is 6. 
Result so far: 86.0
Subtracting 6 from 6 leaves us with 0.
Grab the next digit (3) from the dividend, add it to 0, then carry on: 3 / 1

Going ahead to step 3:
1 can be fit into 3 3 times, resulting in a remainder of 0.
The number 3 becomes the next digit in our result. 
Result so far: 863.0
Subtracting 3 from 3 leaves us with 0.
Bring next digit (9) of the dividend behind the 0 and repeat the process: 9 / 1

Let's proceed to step 4:
When dividing 9 by 1, we get 9 with a remainder of 0.
Put 9 as the next digit of the answer. 
Result so far: 8639.0
If we take 9 away from 9, we end up with 0.
Include the next digit (9) from the dividend after 0, then repeat: 9 / 1

Going ahead to step 5:
If we divide 9 by 1, we get 9 and a remainder of 0.
Use 9 as the next digit of our solution. 
Result so far: 86399.0
The remainder is 0 after subtracting 9 from 9.
Take the next digit (8) from the dividend and append it to 0, then repeat: 8 / 1

Moving on to step 6:
When dividing 8 by 1, we get 8 with a remainder of 0.
Record the quotient 8 as the next digit in the result. 
Result so far: 863998.0
The remainder is 0 after subtracting 8 from 8.
Take the next digit (8) from the dividend and append it to 0, then repeat: 8 / 1

Going ahead to step 7:
If we divide 8 by 1, we get 8 and a remainder of 0.
Record the quotient 8 as the next digit in the result. 
Result so far: 8639988.0
If we take 8 away from 8, we end up with 0.
Grab the next digit (9) from the dividend, add it to 0, then carry on: 9 / 1

Going ahead to step 8:
When dividing 9 by 1, we get 9 with a remainder of 0.
Use 9 as the next digit of our solution. 
Result so far: 86399889.0
The remainder is 0 after subtracting 9 from 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 9:
The number 1 fits into 0 0 times, leaving a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 86399889.0
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 10:
1 can be fit into 0 0 times, resulting in a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 86399889.0
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

After the division, we end up with 86399889.0 and a remainder of 0.0.