We look at the division of 72123 by 45 
We're looking to find how many times 45 goes into 72123.

Going ahead to step 1:
If we divide 7 by 45, we get 0 and a remainder of 7.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 7, we get 7.
Grab the next digit (2) from the dividend, add it to 7, then carry on: 72 / 45

Let's proceed to step 2:
If we divide 72 by 45, we get 1 and a remainder of 27.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
The remainder is 27 after subtracting 45 from 72.
Bring next digit (1) of the dividend behind the 27 and repeat the process: 271 / 45

Let's proceed to step 3:
If we divide 271 by 45, we get 6 and a remainder of 1.
The next digit of our result is 6. 
Result so far: 16.0
The remainder is 1 after subtracting 270 from 271.
Include the next digit (2) from the dividend after 1, then repeat: 12 / 45

Moving on to step 4:
The number 45 fits into 12 0 times, leaving a remainder of 12.
Put 0 as the next digit of the answer. 
Result so far: 160.0
If we take 0 away from 12, we end up with 12.
Fetch the next digit (3) from the dividend, attach it to 12 and continue: 123 / 45

Going ahead to step 5:
The number 45 fits into 123 2 times, leaving a remainder of 33.
Use 2 as the next digit of our solution. 
Result so far: 1602.0
The remainder is 33 after subtracting 90 from 123.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

Step 6:
When dividing 330 by 45, we get 7 with a remainder of 15.
Use 7 as the next digit of our solution. 
Result so far: 1602.7
Deduct 315 from 330 and we're left 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.

Advancing to step 7:
150 divided by 45 is 3 with a remainder of 15.
Use 3 as the next digit of our solution. 
Result so far: 1602.73
Subtract 135 from 150 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 8:
45 can be fit into 150 3 times, resulting in a remainder of 15.
Use 3 as the next digit of our solution. 
Result so far: 1602.733
The remainder is 15 after subtracting 135 from 150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

The final result is 1602.733 with a remainder of 0.0015.