644770 ÷ 72 
We're looking to find how many times 72 goes into 644770.

On to step 1:
72 goes into 6 0 times with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Grab the next digit (4) from the dividend, add it to 6, then carry on: 64 / 72

Going ahead to step 2:
72 goes into 64 0 times with a remainder of 64.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 64 to get 64.
Grab the next digit (4) from the dividend, add it to 64, then carry on: 644 / 72

Going ahead to step 3:
When dividing 644 by 72, we get 8 with a remainder of 68.
Use 8 as the next digit of our solution. 
Result so far: 8.0
Subtract 576 from 644 to get 68.
Append the next digit (7) from the dividend to 68 and continue with: 687 / 72

Step 4:
72 goes into 687 9 times with a remainder of 39.
The number 9 becomes the next digit in our result. 
Result so far: 89.0
Subtracting 648 from 687 leaves us with 39.
Include the next digit (7) from the dividend after 39, then repeat: 397 / 72

On to step 5:
When dividing 397 by 72, we get 5 with a remainder of 37.
The next digit of our result is 5. 
Result so far: 895.0
Subtracting 360 from 397 leaves us with 37.
Fetch the next digit (0) from the dividend, attach it to 37 and continue: 370 / 72

Moving on to step 6:
When dividing 370 by 72, we get 5 with a remainder of 10.
Put 5 as the next digit of the answer. 
Result so far: 8955.0
If we take 360 away from 370, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 7:
72 goes into 100 1 times with a remainder of 28.
Record the quotient 1 as the next digit in the result. 
Result so far: 8955.1
Deduct 72 from 100 and we're left with 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Moving on to step 8:
If we divide 280 by 72, we get 3 and a remainder of 64.
Put 3 as the next digit of the answer. 
Result so far: 8955.13
Subtracting 216 from 280 leaves us with 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

On to step 9:
640 divided by 72 is 8 with a remainder of 64.
Put 8 as the next digit of the answer. 
Result so far: 8955.138
Deduct 576 from 640 and we're left with 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

Step 10:
72 goes into 640 8 times with a remainder of 64.
Write down 8 as next digit of the result. 
Result so far: 8955.1388
Deduct 576 from 640 and we're left with 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

The final outcome is 8955.1388, with a leftover of 0.00064.