645143 ÷ 72 
We're looking to find how many times 72 goes into 645143.

Step 1:
When dividing 6 by 72, we get 0 with a remainder of 6.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 72

Going ahead to step 2:
If we divide 64 by 72, we get 0 and a remainder of 64.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 64 to get 64.
Bring next digit (5) of the dividend behind the 64 and repeat the process: 645 / 72

Advancing to step 3:
When dividing 645 by 72, we get 8 with a remainder of 69.
The next digit of our result is 8. 
Result so far: 8.0
Subtracting 576 from 645 leaves us with 69.
Bring next digit (1) of the dividend behind the 69 and repeat the process: 691 / 72

Let's proceed to step 4:
The number 72 fits into 691 9 times, leaving a remainder of 43.
Use 9 as the next digit of our solution. 
Result so far: 89.0
Deduct 648 from 691 and we're left with 43.
Take the next digit (4) from the dividend and append it to 43, then repeat: 434 / 72

On to step 5:
The number 72 fits into 434 6 times, leaving a remainder of 2.
Use 6 as the next digit of our solution. 
Result so far: 896.0
Deduct 432 from 434 and we're left with 2.
Include the next digit (3) from the dividend after 2, then repeat: 23 / 72

Going ahead to step 6:
When dividing 23 by 72, we get 0 with a remainder of 23.
Write down 0 as next digit of the result. 
Result so far: 8960.0
If we subtract 0 from 23, we get 23.
Since there are no more digits in the dividend, we add a zero to the remainder making it 230, and continue the process.

Let's proceed to step 7:
If we divide 230 by 72, we get 3 and a remainder of 14.
Write down 3 as next digit of the result. 
Result so far: 8960.3
If we subtract 216 from 230, we get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Step 8:
140 divided by 72 is 1 with a remainder of 68.
Write down 1 as next digit of the result. 
Result so far: 8960.31
Subtract 72 from 140 to get 68.
Since there are no more digits in the dividend, we add a zero to the remainder making it 680, and continue the process.

Let's proceed to step 9:
72 can be fit into 680 9 times, resulting in a remainder of 32.
Use 9 as the next digit of our solution. 
Result so far: 8960.319
Subtracting 648 from 680 leaves us with 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

Step 10:
When dividing 320 by 72, we get 4 with a remainder of 32.
Use 4 as the next digit of our solution. 
Result so far: 8960.3194
Subtract 288 from 320 to get 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

On to step 11:
The number 72 fits into 320 4 times, leaving a remainder of 32.
Record the quotient 4 as the next digit in the result. 
Result so far: 8960.31944
Subtracting 288 from 320 leaves us with 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

Our division results in 8960.31944 with a remaining 3.2e-05.