We look at the division of 815371 by 66 
Let's see how many times 66 fits into 815371.

Step 1:
The number 66 fits into 8 0 times, leaving a remainder of 8.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 8, we get 8.
Take the next digit (1) from the dividend and append it to 8, then repeat: 81 / 66

On to step 2:
The number 66 fits into 81 1 times, leaving a remainder of 15.
The next digit of our result is 1. 
Result so far: 1.0
Deduct 66 from 81 and we're left with 15.
Include the next digit (5) from the dividend after 15, then repeat: 155 / 66

Moving on to step 3:
66 can be fit into 155 2 times, resulting in a remainder of 23.
The number 2 becomes the next digit in our result. 
Result so far: 12.0
The remainder is 23 after subtracting 132 from 155.
Fetch the next digit (3) from the dividend, attach it to 23 and continue: 233 / 66

Advancing to step 4:
The number 66 fits into 233 3 times, leaving a remainder of 35.
The number 3 becomes the next digit in our result. 
Result so far: 123.0
The remainder is 35 after subtracting 198 from 233.
Fetch the next digit (7) from the dividend, attach it to 35 and continue: 357 / 66

On to step 5:
66 goes into 357 5 times with a remainder of 27.
Record the quotient 5 as the next digit in the result. 
Result so far: 1235.0
The remainder is 27 after subtracting 330 from 357.
Include the next digit (1) from the dividend after 27, then repeat: 271 / 66

Let's proceed to step 6:
66 can be fit into 271 4 times, resulting in a remainder of 7.
Write down 4 as next digit of the result. 
Result so far: 12354.0
Deduct 264 from 271 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

On to step 7:
If we divide 70 by 66, we get 1 and a remainder of 4.
Put 1 as the next digit of the answer. 
Result so far: 12354.1
If we take 66 away from 70, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Let's proceed to step 8:
The number 66 fits into 40 0 times, leaving a remainder of 40.
Record the quotient 0 as the next digit in the result. 
Result so far: 12354.1
Deduct 0 from 40 and we're left with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

On to step 9:
When dividing 400 by 66, we get 6 with a remainder of 4.
The next digit of our result is 6. 
Result so far: 12354.106
The remainder is 4 after subtracting 396 from 400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 10:
40 divided by 66 is 0 with a remainder of 40.
The number 0 becomes the next digit in our result. 
Result so far: 12354.106
The remainder is 40 after subtracting 0 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Going ahead to step 11:
When dividing 400 by 66, we get 6 with a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 12354.10606
Deduct 396 from 400 and we're left with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 12:
66 can be fit into 40 0 times, resulting in a remainder of 40.
The next digit of our result is 0. 
Result so far: 12354.10606
Subtracting 0 from 40 leaves us with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

On to step 13:
When dividing 400 by 66, we get 6 with a remainder of 4.
The number 6 becomes the next digit in our result. 
Result so far: 12354.1060606
The remainder is 4 after subtracting 396 from 400.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Going ahead to step 14:
66 can be fit into 40 0 times, resulting in a remainder of 40.
Use 0 as the next digit of our solution. 
Result so far: 12354.1060606
Deduct 0 from 40 and we're left with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

The final outcome is 12354.1060606, with a leftover of 4e-08.