We're dividing 451840 by 90 
We're looking to find how many times 90 goes into 451840.

Step 1:
90 can be fit into 4 0 times, resulting in a remainder of 4.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 4, we end up with 4.
Grab the next digit (5) from the dividend, add it to 4, then carry on: 45 / 90

Step 2:
If we divide 45 by 90, we get 0 and a remainder of 45.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 45 after subtracting 0 from 45.
Append the next digit (1) from the dividend to 45 and continue with: 451 / 90

Going ahead to step 3:
The number 90 fits into 451 5 times, leaving a remainder of 1.
Write down 5 as next digit of the result. 
Result so far: 5.0
Subtracting 450 from 451 leaves us with 1.
Append the next digit (8) from the dividend to 1 and continue with: 18 / 90

Going ahead to step 4:
The number 90 fits into 18 0 times, leaving a remainder of 18.
Use 0 as the next digit of our solution. 
Result so far: 50.0
If we subtract 0 from 18, we get 18.
Append the next digit (4) from the dividend to 18 and continue with: 184 / 90

Step 5:
90 can be fit into 184 2 times, resulting in a remainder of 4.
Put 2 as the next digit of the answer. 
Result so far: 502.0
The remainder is 4 after subtracting 180 from 184.
Bring next digit (0) of the dividend behind the 4 and repeat the process: 40 / 90

Advancing to step 6:
If we divide 40 by 90, we get 0 and a remainder of 40.
The next digit of our result is 0. 
Result so far: 5020.0
Subtracting 0 from 40 leaves us with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Advancing to step 7:
If we divide 400 by 90, we get 4 and a remainder of 40.
The next digit of our result is 4. 
Result so far: 5020.4
If we take 360 away from 400, we end up with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

Step 8:
When dividing 400 by 90, we get 4 with a remainder of 40.
Put 4 as the next digit of the answer. 
Result so far: 5020.44
Subtracting 360 from 400 leaves us with 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

After the division, we end up with 5020.44 and a remainder of 0.04.