15811561 ÷ 805 
We want to figure out the number of times 15811561 can be divided by 805.

Step 1:
When dividing 1 by 805, we get 0 with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Append the next digit (5) from the dividend to 1 and continue with: 15 / 805

Step 2:
When dividing 15 by 805, we get 0 with a remainder of 15.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 15 and we're left with 15.
Fetch the next digit (8) from the dividend, attach it to 15 and continue: 158 / 805

Going ahead to step 3:
805 can be fit into 158 0 times, resulting in a remainder of 158.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 158 to get 158.
Append the next digit (1) from the dividend to 158 and continue with: 1581 / 805

Let's proceed to step 4:
When dividing 1581 by 805, we get 1 with a remainder of 776.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Deduct 805 from 1581 and we're left with 776.
Include the next digit (1) from the dividend after 776, then repeat: 7761 / 805

Moving on to step 5:
805 can be fit into 7761 9 times, resulting in a remainder of 516.
Record the quotient 9 as the next digit in the result. 
Result so far: 19.0
Subtracting 7245 from 7761 leaves us with 516.
Append the next digit (5) from the dividend to 516 and continue with: 5165 / 805

Moving on to step 6:
5165 divided by 805 is 6 with a remainder of 335.
Use 6 as the next digit of our solution. 
Result so far: 196.0
If we take 4830 away from 5165, we end up with 335.
Fetch the next digit (6) from the dividend, attach it to 335 and continue: 3356 / 805

On to step 7:
When dividing 3356 by 805, we get 4 with a remainder of 136.
Use 4 as the next digit of our solution. 
Result so far: 1964.0
The remainder is 136 after subtracting 3220 from 3356.
Grab the next digit (1) from the dividend, add it to 136, then carry on: 1361 / 805

Moving on to step 8:
The number 805 fits into 1361 1 times, leaving a remainder of 556.
The number 1 becomes the next digit in our result. 
Result so far: 19641.0
If we take 805 away from 1361, we end up with 556.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5560, and continue the process.

On to step 9:
805 goes into 5560 6 times with a remainder of 730.
The number 6 becomes the next digit in our result. 
Result so far: 19641.6
If we take 4830 away from 5560, we end up with 730.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7300, and continue the process.

Advancing to step 10:
The number 805 fits into 7300 9 times, leaving a remainder of 55.
Put 9 as the next digit of the answer. 
Result so far: 19641.69
Deduct 7245 from 7300 and we're left with 55.
Since there are no more digits in the dividend, we add a zero to the remainder making it 550, and continue the process.

Advancing to step 11:
When dividing 550 by 805, we get 0 with a remainder of 550.
Record the quotient 0 as the next digit in the result. 
Result so far: 19641.69
The remainder is 550 after subtracting 0 from 550.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5500, and continue the process.

Going ahead to step 12:
805 goes into 5500 6 times with a remainder of 670.
The number 6 becomes the next digit in our result. 
Result so far: 19641.6906
Subtract 4830 from 5500 to get 670.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6700, and continue the process.

Going ahead to step 13:
When dividing 6700 by 805, we get 8 with a remainder of 260.
Use 8 as the next digit of our solution. 
Result so far: 19641.69068
The remainder is 260 after subtracting 6440 from 6700.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2600, and continue the process.

Going ahead to step 14:
805 goes into 2600 3 times with a remainder of 185.
The number 3 becomes the next digit in our result. 
Result so far: 19641.690683
The remainder is 185 after subtracting 2415 from 2600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1850, and continue the process.

Step 15:
When dividing 1850 by 805, we get 2 with a remainder of 240.
The number 2 becomes the next digit in our result. 
Result so far: 19641.6906832
Deduct 1610 from 1850 and we're left with 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2400, and continue the process.

Advancing to step 16:
If we divide 2400 by 805, we get 2 and a remainder of 790.
Use 2 as the next digit of our solution. 
Result so far: 19641.69068322
Deduct 1610 from 2400 and we're left with 790.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7900, and continue the process.

In conclusion, the division gives 19641.69068322 with a balance of 7.9e-07.