Let's divide 399973 by 90
We want to divide 399973 by 90.

Going ahead to step 1:
If we divide 3 by 90, we get 0 and a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 3 after subtracting 0 from 3.
Append the next digit (9) from the dividend to 3 and continue with: 39 / 90

Let's proceed to step 2:
The number 90 fits into 39 0 times, leaving a remainder of 39.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 39 leaves us with 39.
Fetch the next digit (9) from the dividend, attach it to 39 and continue: 399 / 90

Step 3:
When dividing 399 by 90, we get 4 with a remainder of 39.
The next digit of our result is 4. 
Result so far: 4.0
If we take 360 away from 399, we end up with 39.
Take the next digit (9) from the dividend and append it to 39, then repeat: 399 / 90

Going ahead to step 4:
The number 90 fits into 399 4 times, leaving a remainder of 39.
Record the quotient 4 as the next digit in the result. 
Result so far: 44.0
Subtract 360 from 399 to get 39.
Take the next digit (7) from the dividend and append it to 39, then repeat: 397 / 90

Advancing to step 5:
When dividing 397 by 90, we get 4 with a remainder of 37.
The number 4 becomes the next digit in our result. 
Result so far: 444.0
If we subtract 360 from 397, we get 37.
Fetch the next digit (3) from the dividend, attach it to 37 and continue: 373 / 90

Going ahead to step 6:
If we divide 373 by 90, we get 4 and a remainder of 13.
Use 4 as the next digit of our solution. 
Result so far: 4444.0
The remainder is 13 after subtracting 360 from 373.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Going ahead to step 7:
If we divide 130 by 90, we get 1 and a remainder of 40.
Use 1 as the next digit of our solution. 
Result so far: 4444.1
Subtract 90 from 130 to get 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 8:
400 divided by 90 is 4 with a remainder of 40.
Put 4 as the next digit of the answer. 
Result so far: 4444.14
Subtract 360 from 400 to get 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 400, and continue the process.

On to step 9:
When dividing 400 by 90, we get 4 with a remainder of 40.
Write down 4 as next digit of the result. 
Result so far: 4444.144
Deduct 360 from 400 and we're left 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.

The final outcome is 4444.144, with a leftover of 0.004.