We look at the division of 78576391 by 166 
Our goal is to divide 78576391 by 166.

Moving on to step 1:
If we divide 7 by 166, we get 0 and a remainder of 7.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 7 and we're left with 7.
Include the next digit (8) from the dividend after 7, then repeat: 78 / 166

Let's proceed to step 2:
If we divide 78 by 166, we get 0 and a remainder of 78.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 78 after subtracting 0 from 78.
Append the next digit (5) from the dividend to 78 and continue with: 785 / 166

Going ahead to step 3:
785 divided by 166 is 4 with a remainder of 121.
Write down 4 as next digit of the result. 
Result so far: 4.0
Subtract 664 from 785 to get 121.
Bring next digit (7) of the dividend behind the 121 and repeat the process: 1217 / 166

Let's proceed to step 4:
166 goes into 1217 7 times with a remainder of 55.
Put 7 as the next digit of the answer. 
Result so far: 47.0
Deduct 1162 from 1217 and we're left with 55.
Bring next digit (6) of the dividend behind the 55 and repeat the process: 556 / 166

Advancing to step 5:
166 goes into 556 3 times with a remainder of 58.
Put 3 as the next digit of the answer. 
Result so far: 473.0
Subtract 498 from 556 to get 58.
Take the next digit (3) from the dividend and append it to 58, then repeat: 583 / 166

Advancing to step 6:
The number 166 fits into 583 3 times, leaving a remainder of 85.
The next digit of our result is 3. 
Result so far: 4733.0
Subtracting 498 from 583 leaves us with 85.
Fetch the next digit (9) from the dividend, attach it to 85 and continue: 859 / 166

Let's proceed to step 7:
When dividing 859 by 166, we get 5 with a remainder of 29.
Record the quotient 5 as the next digit in the result. 
Result so far: 47335.0
Subtracting 830 from 859 leaves us with 29.
Bring next digit (1) of the dividend behind the 29 and repeat the process: 291 / 166

On to step 8:
The number 166 fits into 291 1 times, leaving a remainder of 125.
Put 1 as the next digit of the answer. 
Result so far: 473351.0
Deduct 166 from 291 and we're left with 125.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1250, and continue the process.

Moving on to step 9:
1250 divided by 166 is 7 with a remainder of 88.
Record the quotient 7 as the next digit in the result. 
Result so far: 473351.7
If we subtract 1162 from 1250, we get 88.
Since there are no more digits in the dividend, we add a zero to the remainder making it 880, and continue the process.

Advancing to step 10:
The number 166 fits into 880 5 times, leaving a remainder of 50.
The next digit of our result is 5. 
Result so far: 473351.75
Subtracting 830 from 880 leaves us with 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 500, and continue the process.

Going ahead to step 11:
The number 166 fits into 500 3 times, leaving a remainder of 2.
Use 3 as the next digit of our solution. 
Result so far: 473351.753
Subtracting 498 from 500 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.

Going ahead to step 12:
If we divide 20 by 166, we get 0 and a remainder of 20.
The number 0 becomes the next digit in our result. 
Result so far: 473351.753
Deduct 0 from 20 and we're left with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

On to step 13:
When dividing 200 by 166, we get 1 with a remainder of 34.
The next digit of our result is 1. 
Result so far: 473351.75301
If we subtract 166 from 200, we get 34.
Since there are no more digits in the dividend, we add a zero to the remainder making it 340, and continue the process.

Moving on to step 14:
When dividing 340 by 166, we get 2 with a remainder of 8.
The number 2 becomes the next digit in our result. 
Result so far: 473351.753012
Deduct 332 from 340 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Advancing to step 15:
166 goes into 80 0 times with a remainder of 80.
Use 0 as the next digit of our solution. 
Result so far: 473351.753012
The remainder is 80 after subtracting 0 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Step 16:
800 divided by 166 is 4 with a remainder of 136.
Record the quotient 4 as the next digit in the result. 
Result so far: 473351.75301204
Subtracting 664 from 800 leaves us with 136.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1360, and continue the process.

The final outcome is 473351.75301204, with a leftover of 1.36e-07.