We look at the division of 123399 by 16 
Our goal is to divide 123399 by 16.

Let's proceed to step 1:
If we divide 1 by 16, we get 0 and a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 1 and we're left with 1.
Include the next digit (2) from the dividend after 1, then repeat: 12 / 16

Going ahead to step 2:
16 goes into 12 0 times with a remainder of 12.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 12 after subtracting 0 from 12.
Include the next digit (3) from the dividend after 12, then repeat: 123 / 16

Step 3:
16 goes into 123 7 times with a remainder of 11.
Write down 7 as next digit of the result. 
Result so far: 7.0
If we take 112 away from 123, we end up with 11.
Append the next digit (3) from the dividend to 11 and continue with: 113 / 16

Advancing to step 4:
The number 16 fits into 113 7 times, leaving a remainder of 1.
Record the quotient 7 as the next digit in the result. 
Result so far: 77.0
If we take 112 away from 113, we end up with 1.
Append the next digit (9) from the dividend to 1 and continue with: 19 / 16

Let's proceed to step 5:
19 divided by 16 is 1 with a remainder of 3.
Use 1 as the next digit of our solution. 
Result so far: 771.0
If we subtract 16 from 19, we get 3.
Grab the next digit (9) from the dividend, add it to 3, then carry on: 39 / 16

Advancing to step 6:
The number 16 fits into 39 2 times, leaving a remainder of 7.
The next digit of our result is 2. 
Result so far: 7712.0
Deduct 32 from 39 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Moving on to step 7:
16 goes into 70 4 times with a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 7712.4
Deduct 64 from 70 and we're left 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.

Advancing to step 8:
60 divided by 16 is 3 with a remainder of 12.
Put 3 as the next digit of the answer. 
Result so far: 7712.43
If we subtract 48 from 60, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 9:
16 goes into 120 7 times with a remainder of 8.
The number 7 becomes the next digit in our result. 
Result so far: 7712.437
If we take 112 away from 120, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Going ahead to step 10:
16 can be fit into 80 5 times, resulting in a remainder of 0.
Use 5 as the next digit of our solution. 
Result so far: 7712.4375
The remainder is 0 after subtracting 80 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 11:
16 goes into 0 0 times with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 7712.4375
Subtracting 0 from 0 leaves us 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.

Going ahead to step 12:
16 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 7712.4375
Subtract 0 from 0 to 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.

The final result is 7712.4375 with a remainder of 0.0.