We're dividing 431731 by 90 
We want to figure out the number of times 431731 can be divided by 90.

On to step 1:
90 goes into 4 0 times with a remainder of 4.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Bring next digit (3) of the dividend behind the 4 and repeat the process: 43 / 90

Going ahead to step 2:
If we divide 43 by 90, we get 0 and a remainder of 43.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 43, we end up with 43.
Include the next digit (1) from the dividend after 43, then repeat: 431 / 90

Moving on to step 3:
When dividing 431 by 90, we get 4 with a remainder of 71.
Use 4 as the next digit of our solution. 
Result so far: 4.0
The remainder is 71 after subtracting 360 from 431.
Include the next digit (7) from the dividend after 71, then repeat: 717 / 90

Going ahead to step 4:
When dividing 717 by 90, we get 7 with a remainder of 87.
Record the quotient 7 as the next digit in the result. 
Result so far: 47.0
Subtract 630 from 717 to get 87.
Include the next digit (3) from the dividend after 87, then repeat: 873 / 90

Moving on to step 5:
If we divide 873 by 90, we get 9 and a remainder of 63.
The next digit of our result is 9. 
Result so far: 479.0
If we take 810 away from 873, we end up with 63.
Fetch the next digit (1) from the dividend, attach it to 63 and continue: 631 / 90

On to step 6:
631 divided by 90 is 7 with a remainder of 1.
Use 7 as the next digit of our solution. 
Result so far: 4797.0
Deduct 630 from 631 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.

Moving on to step 7:
If we divide 10 by 90, we get 0 and a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 4797.0
If we take 0 away from 10, we end up with 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 8:
90 can be fit into 100 1 times, resulting in a remainder of 10.
Put 1 as the next digit of the answer. 
Result so far: 4797.01
Subtracting 90 from 100 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Advancing to step 9:
The number 90 fits into 100 1 times, leaving a remainder of 10.
The number 1 becomes the next digit in our result. 
Result so far: 4797.011
If we take 90 away from 100, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Our division results in 4797.011 with a remaining 0.001.