We look at the division of 815717 by 3 
We're looking to find how many times 3 goes into 815717.

Step 1:
When dividing 8 by 3, we get 2 with a remainder of 2.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Deduct 6 from 8 and we're left with 2.
Grab the next digit (1) from the dividend, add it to 2, then carry on: 21 / 3

On to step 2:
3 goes into 21 7 times with a remainder of 0.
The next digit of our result is 7. 
Result so far: 27.0
If we subtract 21 from 21, we get 0.
Grab the next digit (5) from the dividend, add it to 0, then carry on: 5 / 3

Advancing to step 3:
3 goes into 5 1 times with a remainder of 2.
The number 1 becomes the next digit in our result. 
Result so far: 271.0
The remainder is 2 after subtracting 3 from 5.
Bring next digit (7) of the dividend behind the 2 and repeat the process: 27 / 3

On to step 4:
The number 3 fits into 27 9 times, leaving a remainder of 0.
Put 9 as the next digit of the answer. 
Result so far: 2719.0
If we take 27 away from 27, we end up with 0.
Grab the next digit (1) from the dividend, add it to 0, then carry on: 1 / 3

On to step 5:
When dividing 1 by 3, we get 0 with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 27190.0
Subtracting 0 from 1 leaves us with 1.
Append the next digit (7) from the dividend to 1 and continue with: 17 / 3

Step 6:
If we divide 17 by 3, we get 5 and a remainder of 2.
Write down 5 as next digit of the result. 
Result so far: 271905.0
If we take 15 away from 17, we end up with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 7:
When dividing 20 by 3, we get 6 with a remainder of 2.
Use 6 as the next digit of our solution. 
Result so far: 271905.6
Subtract 18 from 20 to get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 8:
When dividing 20 by 3, we get 6 with a remainder of 2.
The number 6 becomes the next digit in our result. 
Result so far: 271905.66
Subtracting 18 from 20 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

After the division, we end up with 271905.66 and a remainder of 0.002.