We're dividing 421355 by 18 
We want to figure out the number of times 421355 can be divided by 18.

Going ahead to step 1:
When dividing 4 by 18, we get 0 with a remainder of 4.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 4 leaves us with 4.
Include the next digit (2) from the dividend after 4, then repeat: 42 / 18

Advancing to step 2:
18 goes into 42 2 times with a remainder of 6.
Record the quotient 2 as the next digit in the result. 
Result so far: 2.0
Subtract 36 from 42 to get 6.
Append the next digit (1) from the dividend to 6 and continue with: 61 / 18

Advancing to step 3:
18 can be fit into 61 3 times, resulting in a remainder of 7.
Write down 3 as next digit of the result. 
Result so far: 23.0
If we subtract 54 from 61, we get 7.
Take the next digit (3) from the dividend and append it to 7, then repeat: 73 / 18

Moving on to step 4:
The number 18 fits into 73 4 times, leaving a remainder of 1.
Put 4 as the next digit of the answer. 
Result so far: 234.0
If we take 72 away from 73, we end up with 1.
Bring next digit (5) of the dividend behind the 1 and repeat the process: 15 / 18

Moving on to step 5:
If we divide 15 by 18, we get 0 and a remainder of 15.
The number 0 becomes the next digit in our result. 
Result so far: 2340.0
If we take 0 away from 15, we end up with 15.
Take the next digit (5) from the dividend and append it to 15, then repeat: 155 / 18

Step 6:
18 can be fit into 155 8 times, resulting in a remainder of 11.
The number 8 becomes the next digit in our result. 
Result so far: 23408.0
Subtracting 144 from 155 leaves us with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Going ahead to step 7:
18 can be fit into 110 6 times, resulting in a remainder of 2.
Put 6 as the next digit of the answer. 
Result so far: 23408.6
If we subtract 108 from 110, we get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Step 8:
When dividing 20 by 18, we get 1 with a remainder of 2.
Put 1 as the next digit of the answer. 
Result so far: 23408.61
Subtracting 18 from 20 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 9:
20 divided by 18 is 1 with a remainder of 2.
Use 1 as the next digit of our solution. 
Result so far: 23408.611
If we take 18 away from 20, we end up with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Our division results in 23408.611 with a remaining 0.0002.