639583 ÷ 45 
We're looking to find how many times 45 goes into 639583.

Step 1:
45 goes into 6 0 times with a remainder of 6.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Include the next digit (3) from the dividend after 6, then repeat: 63 / 45

Going ahead to step 2:
If we divide 63 by 45, we get 1 and a remainder of 18.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Deduct 45 from 63 and we're left with 18.
Take the next digit (9) from the dividend and append it to 18, then repeat: 189 / 45

Step 3:
If we divide 189 by 45, we get 4 and a remainder of 9.
Use 4 as the next digit of our solution. 
Result so far: 14.0
If we subtract 180 from 189, we get 9.
Include the next digit (5) from the dividend after 9, then repeat: 95 / 45

Let's proceed to step 4:
The number 45 fits into 95 2 times, leaving a remainder of 5.
Use 2 as the next digit of our solution. 
Result so far: 142.0
Subtracting 90 from 95 leaves us with 5.
Append the next digit (8) from the dividend to 5 and continue with: 58 / 45

Going ahead to step 5:
45 can be fit into 58 1 times, resulting in a remainder of 13.
The next digit of our result is 1. 
Result so far: 1421.0
The remainder is 13 after subtracting 45 from 58.
Fetch the next digit (3) from the dividend, attach it to 13 and continue: 133 / 45

Step 6:
The number 45 fits into 133 2 times, leaving a remainder of 43.
Write down 2 as next digit of the result. 
Result so far: 14212.0
Subtracting 90 from 133 leaves us with 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 430, and continue the process.

Advancing to step 7:
The number 45 fits into 430 9 times, leaving a remainder of 25.
Put 9 as the next digit of the answer. 
Result so far: 14212.9
The remainder is 25 after subtracting 405 from 430.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Step 8:
45 goes into 250 5 times with a remainder of 25.
Put 5 as the next digit of the answer. 
Result so far: 14212.95
If we subtract 225 from 250, we get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Moving on to step 9:
45 goes into 250 5 times with a remainder of 25.
The number 5 becomes the next digit in our result. 
Result so far: 14212.955
If we subtract 225 from 250, we get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

The final result is 14212.955 with a remainder of 0.0025.