639693 ÷ 81 
We're looking to find how many times 81 goes into 639693.

Advancing to step 1:
81 goes into 6 0 times with a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Grab the next digit (3) from the dividend, add it to 6, then carry on: 63 / 81

Moving on to step 2:
63 divided by 81 is 0 with a remainder of 63.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 63 and we're left with 63.
Bring next digit (9) of the dividend behind the 63 and repeat the process: 639 / 81

Step 3:
When dividing 639 by 81, we get 7 with a remainder of 72.
Record the quotient 7 as the next digit in the result. 
Result so far: 7.0
Subtracting 567 from 639 leaves us with 72.
Grab the next digit (6) from the dividend, add it to 72, then carry on: 726 / 81

Going ahead to step 4:
726 divided by 81 is 8 with a remainder of 78.
Record the quotient 8 as the next digit in the result. 
Result so far: 78.0
Subtract 648 from 726 to get 78.
Append the next digit (9) from the dividend to 78 and continue with: 789 / 81

Let's proceed to step 5:
81 goes into 789 9 times with a remainder of 60.
Record the quotient 9 as the next digit in the result. 
Result so far: 789.0
The remainder is 60 after subtracting 729 from 789.
Bring next digit (3) of the dividend behind the 60 and repeat the process: 603 / 81

Advancing to step 6:
603 divided by 81 is 7 with a remainder of 36.
Put 7 as the next digit of the answer. 
Result so far: 7897.0
Subtracting 567 from 603 leaves us with 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Going ahead to step 7:
81 goes into 360 4 times with a remainder of 36.
Use 4 as the next digit of our solution. 
Result so far: 7897.4
Subtract 324 from 360 to get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Let's proceed to step 8:
81 can be fit into 360 4 times, resulting in a remainder of 36.
Record the quotient 4 as the next digit in the result. 
Result so far: 7897.44
If we subtract 324 from 360, we get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

The final result is 7897.44 with a remainder of 0.036.