81190666 ÷ 645 
We want to figure out the number of times 81190666 can be divided by 645.

On to step 1:
645 can be fit into 8 0 times, resulting in a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Include the next digit (1) from the dividend after 8, then repeat: 81 / 645

Let's proceed to step 2:
If we divide 81 by 645, we get 0 and a remainder of 81.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 81, we get 81.
Append the next digit (1) from the dividend to 81 and continue with: 811 / 645

Step 3:
811 divided by 645 is 1 with a remainder of 166.
The next digit of our result is 1. 
Result so far: 1.0
Subtract 645 from 811 to get 166.
Append the next digit (9) from the dividend to 166 and continue with: 1669 / 645

Advancing to step 4:
1669 divided by 645 is 2 with a remainder of 379.
Write down 2 as next digit of the result. 
Result so far: 12.0
If we subtract 1290 from 1669, we get 379.
Fetch the next digit (0) from the dividend, attach it to 379 and continue: 3790 / 645

Let's proceed to step 5:
When dividing 3790 by 645, we get 5 with a remainder of 565.
Use 5 as the next digit of our solution. 
Result so far: 125.0
Deduct 3225 from 3790 and we're left with 565.
Fetch the next digit (6) from the dividend, attach it to 565 and continue: 5656 / 645

On to step 6:
When dividing 5656 by 645, we get 8 with a remainder of 496.
Put 8 as the next digit of the answer. 
Result so far: 1258.0
Subtracting 5160 from 5656 leaves us with 496.
Bring next digit (6) of the dividend behind the 496 and repeat the process: 4966 / 645

Let's proceed to step 7:
If we divide 4966 by 645, we get 7 and a remainder of 451.
Use 7 as the next digit of our solution. 
Result so far: 12587.0
If we take 4515 away from 4966, we end up with 451.
Bring next digit (6) of the dividend behind the 451 and repeat the process: 4516 / 645

Going ahead to step 8:
4516 divided by 645 is 7 with a remainder of 1.
Put 7 as the next digit of the answer. 
Result so far: 125877.0
Deduct 4515 from 4516 and we're left with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Going ahead to step 9:
When dividing 10 by 645, we get 0 with a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 125877.0
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 10:
645 can be fit into 100 0 times, resulting in a remainder of 100.
Write down 0 as next digit of the result. 
Result so far: 125877.0
Subtract 0 from 100 to get 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1000, and continue the process.

The final result is 125877.0 with a remainder of 0.1.