We're dividing 51012 by 3 
Let's see how many times 3 fits into 51012.

Going ahead to step 1:
3 goes into 5 1 times with a remainder of 2.
The next digit of our result is 1. 
Result so far: 1.0
Deduct 3 from 5 and we're left with 2.
Include the next digit (1) from the dividend after 2, then repeat: 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: 17.0
Subtracting 21 from 21 leaves us with 0.
Append the next digit (0) from the dividend to 0 and continue with: 0 / 3

Moving on to step 3:
3 goes into 0 0 times with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 170.0
Subtracting 0 from 0 leaves us with 0.
Take the next digit (1) from the dividend and append it to 0, then repeat: 1 / 3

Step 4:
3 can be fit into 1 0 times, resulting in a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 1700.0
Subtract 0 from 1 to get 1.
Take the next digit (2) from the dividend and append it to 1, then repeat: 12 / 3

On to step 5:
If we divide 12 by 3, we get 4 and a remainder of 0.
Put 4 as the next digit of the answer. 
Result so far: 17004.0
Subtracting 12 from 12 leaves us 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.

Let's proceed to step 6:
When dividing 0 by 3, we get 0 with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 17004.0
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.

Let's proceed to step 7:
The number 3 fits into 0 0 times, leaving a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 17004.0
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.

The final result is 17004.0 with a remainder of 0.0.