421749 ÷ 90 
Our goal is to divide 421749 by 90.

Going ahead to step 1:
The number 90 fits into 4 0 times, leaving a remainder of 4.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 4 leaves us with 4.
Take the next digit (2) from the dividend and append it to 4, then repeat: 42 / 90

Going ahead to step 2:
42 divided by 90 is 0 with a remainder of 42.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 42 and we're left with 42.
Take the next digit (1) from the dividend and append it to 42, then repeat: 421 / 90

Step 3:
421 divided by 90 is 4 with a remainder of 61.
Put 4 as the next digit of the answer. 
Result so far: 4.0
If we take 360 away from 421, we end up with 61.
Take the next digit (7) from the dividend and append it to 61, then repeat: 617 / 90

Advancing to step 4:
90 goes into 617 6 times with a remainder of 77.
Put 6 as the next digit of the answer. 
Result so far: 46.0
Deduct 540 from 617 and we're left with 77.
Take the next digit (4) from the dividend and append it to 77, then repeat: 774 / 90

Advancing to step 5:
The number 90 fits into 774 8 times, leaving a remainder of 54.
Put 8 as the next digit of the answer. 
Result so far: 468.0
If we subtract 720 from 774, we get 54.
Append the next digit (9) from the dividend to 54 and continue with: 549 / 90

Step 6:
If we divide 549 by 90, we get 6 and a remainder of 9.
Write down 6 as next digit of the result. 
Result so far: 4686.0
If we take 540 away from 549, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Moving on to step 7:
The number 90 fits into 90 1 times, leaving a remainder of 0.
The next digit of our result is 1. 
Result so far: 4686.1
The remainder is 0 after subtracting 90 from 90.
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:
90 goes into 0 0 times with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 4686.1
If we take 0 away from 0, we end up 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.

Moving on to step 9:
If we divide 0 by 90, we get 0 and a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 4686.1
If we take 0 away from 0, we end up 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.

After the division, we end up with 4686.1 and a remainder of 0.0.