243453 ÷ 21 
Let's see how many times 21 fits into 243453.

Moving on to step 1:
If we divide 2 by 21, we get 0 and a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Bring next digit (4) of the dividend behind the 2 and repeat the process: 24 / 21

Moving on to step 2:
21 goes into 24 1 times with a remainder of 3.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we take 21 away from 24, we end up with 3.
Bring next digit (3) of the dividend behind the 3 and repeat the process: 33 / 21

Advancing to step 3:
33 divided by 21 is 1 with a remainder of 12.
The next digit of our result is 1. 
Result so far: 11.0
If we take 21 away from 33, we end up with 12.
Append the next digit (4) from the dividend to 12 and continue with: 124 / 21

Step 4:
21 goes into 124 5 times with a remainder of 19.
Record the quotient 5 as the next digit in the result. 
Result so far: 115.0
If we take 105 away from 124, we end up with 19.
Include the next digit (5) from the dividend after 19, then repeat: 195 / 21

Advancing to step 5:
195 divided by 21 is 9 with a remainder of 6.
The next digit of our result is 9. 
Result so far: 1159.0
Subtracting 189 from 195 leaves us with 6.
Include the next digit (3) from the dividend after 6, then repeat: 63 / 21

Let's proceed to step 6:
If we divide 63 by 21, we get 3 and a remainder of 0.
Record the quotient 3 as the next digit in the result. 
Result so far: 11593.0
If we take 63 away from 63, 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.

Let's proceed to step 7:
If we divide 0 by 21, we get 0 and a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 11593.0
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 8:
The number 21 fits into 0 0 times, leaving a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 11593.0
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Our division results in 11593.0 with a remaining 0.0.