21259 ÷ 18 
Our goal is to divide 21259 by 18.

Moving on to step 1:
18 can be fit into 2 0 times, resulting in a remainder of 2.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 2 and we're left with 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 18

Advancing to step 2:
18 goes into 21 1 times with a remainder of 3.
Use 1 as the next digit of our solution. 
Result so far: 1.0
If we subtract 18 from 21, we get 3.
Grab the next digit (2) from the dividend, add it to 3, then carry on: 32 / 18

Going ahead to step 3:
18 goes into 32 1 times with a remainder of 14.
Put 1 as the next digit of the answer. 
Result so far: 11.0
The remainder is 14 after subtracting 18 from 32.
Grab the next digit (5) from the dividend, add it to 14, then carry on: 145 / 18

Moving on to step 4:
When dividing 145 by 18, we get 8 with a remainder of 1.
Use 8 as the next digit of our solution. 
Result so far: 118.0
The remainder is 1 after subtracting 144 from 145.
Take the next digit (9) from the dividend and append it to 1, then repeat: 19 / 18

On to step 5:
The number 18 fits into 19 1 times, leaving a remainder of 1.
Record the quotient 1 as the next digit in the result. 
Result so far: 1181.0
If we subtract 18 from 19, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 6:
If we divide 10 by 18, we get 0 and a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 1181.0
Deduct 0 from 10 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 7:
100 divided by 18 is 5 with a remainder of 10.
The number 5 becomes the next digit in our result. 
Result so far: 1181.05
If we take 90 away from 100, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Let's proceed to step 8:
100 divided by 18 is 5 with a remainder of 10.
Put 5 as the next digit of the answer. 
Result so far: 1181.055
If we take 90 away from 100, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

The final result is 1181.055 with a remainder of 0.001.