15173855 ÷ 661 
We want to figure out the number of times 15173855 can be divided by 661.

Step 1:
1 divided by 661 is 0 with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 1 and we're left with 1.
Fetch the next digit (5) from the dividend, attach it to 1 and continue: 15 / 661

Moving on to step 2:
When dividing 15 by 661, we get 0 with a remainder of 15.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 15 leaves us with 15.
Bring next digit (1) of the dividend behind the 15 and repeat the process: 151 / 661

Advancing to step 3:
If we divide 151 by 661, we get 0 and a remainder of 151.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 151 and we're left with 151.
Append the next digit (7) from the dividend to 151 and continue with: 1517 / 661

Let's proceed to step 4:
If we divide 1517 by 661, we get 2 and a remainder of 195.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
If we subtract 1322 from 1517, we get 195.
Grab the next digit (3) from the dividend, add it to 195, then carry on: 1953 / 661

On to step 5:
If we divide 1953 by 661, we get 2 and a remainder of 631.
Record the quotient 2 as the next digit in the result. 
Result so far: 22.0
Deduct 1322 from 1953 and we're left with 631.
Fetch the next digit (8) from the dividend, attach it to 631 and continue: 6318 / 661

Advancing to step 6:
When dividing 6318 by 661, we get 9 with a remainder of 369.
Use 9 as the next digit of our solution. 
Result so far: 229.0
Subtracting 5949 from 6318 leaves us with 369.
Fetch the next digit (5) from the dividend, attach it to 369 and continue: 3695 / 661

Let's proceed to step 7:
3695 divided by 661 is 5 with a remainder of 390.
The next digit of our result is 5. 
Result so far: 2295.0
Subtract 3305 from 3695 to get 390.
Fetch the next digit (5) from the dividend, attach it to 390 and continue: 3905 / 661

On to step 8:
3905 divided by 661 is 5 with a remainder of 600.
Use 5 as the next digit of our solution. 
Result so far: 22955.0
Subtract 3305 from 3905 to get 600.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6000, and continue the process.

Let's proceed to step 9:
661 can be fit into 6000 9 times, resulting in a remainder of 51.
Put 9 as the next digit of the answer. 
Result so far: 22955.9
Subtracting 5949 from 6000 leaves us with 51.
Since there are no more digits in the dividend, we add a zero to the remainder making it 510, and continue the process.

Advancing to step 10:
If we divide 510 by 661, we get 0 and a remainder of 510.
Record the quotient 0 as the next digit in the result. 
Result so far: 22955.9
If we subtract 0 from 510, we get 510.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5100, and continue the process.

Step 11:
661 can be fit into 5100 7 times, resulting in a remainder of 473.
Write down 7 as next digit of the result. 
Result so far: 22955.907
Subtract 4627 from 5100 to get 473.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4730, and continue the process.

Advancing to step 12:
The number 661 fits into 4730 7 times, leaving a remainder of 103.
Record the quotient 7 as the next digit in the result. 
Result so far: 22955.9077
If we subtract 4627 from 4730, we get 103.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1030, and continue the process.

After the division, we end up with 22955.9077 and a remainder of 0.00103.