We look at the division of 661573 by 1 
We want to figure out the number of times 661573 can be divided by 1.

On to step 1:
If we divide 6 by 1, we get 6 and a remainder of 0.
Use 6 as the next digit of our solution. 
Result so far: 6.0
If we take 6 away from 6, we end up with 0.
Fetch the next digit (6) from the dividend, attach it to 0 and continue: 6 / 1

Going ahead to step 2:
6 divided by 1 is 6 with a remainder of 0.
Put 6 as the next digit of the answer. 
Result so far: 66.0
If we subtract 6 from 6, we get 0.
Take the next digit (1) from the dividend and append it to 0, then repeat: 1 / 1

Step 3:
When dividing 1 by 1, we get 1 with a remainder of 0.
Use 1 as the next digit of our solution. 
Result so far: 661.0
If we subtract 1 from 1, we get 0.
Take the next digit (5) from the dividend and append it to 0, then repeat: 5 / 1

On to step 4:
1 can be fit into 5 5 times, resulting in a remainder of 0.
The next digit of our result is 5. 
Result so far: 6615.0
The remainder is 0 after subtracting 5 from 5.
Take the next digit (7) from the dividend and append it to 0, then repeat: 7 / 1

Moving on to step 5:
7 divided by 1 is 7 with a remainder of 0.
Record the quotient 7 as the next digit in the result. 
Result so far: 66157.0
If we subtract 7 from 7, we get 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 1

Going ahead to step 6:
1 goes into 3 3 times with a remainder of 0.
Use 3 as the next digit of our solution. 
Result so far: 661573.0
Subtracting 3 from 3 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 7:
0 divided by 1 is 0 with a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 661573.0
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Let's proceed to step 8:
When dividing 0 by 1, we get 0 with a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 661573.0
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The quotient of the division is 661573.0, and the remainder is 0.0.