393991 ÷ 10 
We want to figure out the number of times 393991 can be divided by 10.

On to step 1:
The number 10 fits into 3 0 times, leaving a remainder of 3.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 10

Let's proceed to step 2:
If we divide 39 by 10, we get 3 and a remainder of 9.
Use 3 as the next digit of our solution. 
Result so far: 3.0
Subtracting 30 from 39 leaves us with 9.
Append the next digit (3) from the dividend to 9 and continue with: 93 / 10

Step 3:
When dividing 93 by 10, we get 9 with a remainder of 3.
Use 9 as the next digit of our solution. 
Result so far: 39.0
If we subtract 90 from 93, we get 3.
Grab the next digit (9) from the dividend, add it to 3, then carry on: 39 / 10

Let's proceed to step 4:
When dividing 39 by 10, we get 3 with a remainder of 9.
The number 3 becomes the next digit in our result. 
Result so far: 393.0
Subtract 30 from 39 to get 9.
Grab the next digit (9) from the dividend, add it to 9, then carry on: 99 / 10

Advancing to step 5:
10 can be fit into 99 9 times, resulting in a remainder of 9.
Record the quotient 9 as the next digit in the result. 
Result so far: 3939.0
If we take 90 away from 99, we end up with 9.
Bring next digit (1) of the dividend behind the 9 and repeat the process: 91 / 10

Advancing to step 6:
10 goes into 91 9 times with a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 39399.0
Subtract 90 from 91 to get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 7:
10 goes into 10 1 times with a remainder of 0.
The next digit of our result is 1. 
Result so far: 39399.1
If we take 10 away from 10, we end up 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.

Moving on to step 8:
0 divided by 10 is 0 with a remainder of 0.
The next digit of our result is 0. 
Result so far: 39399.1
If we subtract 0 from 0, we 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.

Advancing to step 9:
0 divided by 10 is 0 with a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 39399.1
If we take 0 away from 0, we end up 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.

The final result is 39399.1 with a remainder of 0.0.