We divide 343521 by 90
We're looking to find how many times 90 goes into 343521.

Advancing to step 1:
The number 90 fits into 3 0 times, leaving a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 3 to get 3.
Fetch the next digit (4) from the dividend, attach it to 3 and continue: 34 / 90

Let's proceed to step 2:
If we divide 34 by 90, we get 0 and a remainder of 34.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 34, we end up with 34.
Bring next digit (3) of the dividend behind the 34 and repeat the process: 343 / 90

Advancing to step 3:
When dividing 343 by 90, we get 3 with a remainder of 73.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Subtract 270 from 343 to get 73.
Grab the next digit (5) from the dividend, add it to 73, then carry on: 735 / 90

Advancing to step 4:
90 goes into 735 8 times with a remainder of 15.
Use 8 as the next digit of our solution. 
Result so far: 38.0
If we take 720 away from 735, we end up with 15.
Fetch the next digit (2) from the dividend, attach it to 15 and continue: 152 / 90

Moving on to step 5:
90 can be fit into 152 1 times, resulting in a remainder of 62.
Write down 1 as next digit of the result. 
Result so far: 381.0
Subtract 90 from 152 to get 62.
Include the next digit (1) from the dividend after 62, then repeat: 621 / 90

Going ahead to step 6:
If we divide 621 by 90, we get 6 and a remainder of 81.
Write down 6 as next digit of the result. 
Result so far: 3816.0
If we subtract 540 from 621, we get 81.
Since there are no more digits in the dividend, we add a zero to the remainder making it 810, and continue the process.

On to step 7:
90 can be fit into 810 9 times, resulting in a remainder of 0.
Record the quotient 9 as the next digit in the result. 
Result so far: 3816.9
If we subtract 810 from 810, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing 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: 3816.9
Subtracting 0 from 0 leaves us 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.

Advancing to step 9:
90 can be fit into 0 0 times, resulting in a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 3816.9
Subtract 0 from 0 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final outcome is 3816.9, with a leftover of 0.0.