305487 divided by 21 
We're looking to find how many times 21 goes into 305487.

Going ahead to step 1:
21 can be fit into 3 0 times, resulting in a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 3 and we're left with 3.
Grab the next digit (0) from the dividend, add it to 3, then carry on: 30 / 21

On to step 2:
When dividing 30 by 21, we get 1 with a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtracting 21 from 30 leaves us with 9.
Grab the next digit (5) from the dividend, add it to 9, then carry on: 95 / 21

On to step 3:
21 can be fit into 95 4 times, resulting in a remainder of 11.
The number 4 becomes the next digit in our result. 
Result so far: 14.0
Subtracting 84 from 95 leaves us with 11.
Include the next digit (4) from the dividend after 11, then repeat: 114 / 21

Going ahead to step 4:
The number 21 fits into 114 5 times, leaving a remainder of 9.
Put 5 as the next digit of the answer. 
Result so far: 145.0
Subtracting 105 from 114 leaves us with 9.
Grab the next digit (8) from the dividend, add it to 9, then carry on: 98 / 21

Going ahead to step 5:
If we divide 98 by 21, we get 4 and a remainder of 14.
Record the quotient 4 as the next digit in the result. 
Result so far: 1454.0
Subtract 84 from 98 to get 14.
Bring next digit (7) of the dividend behind the 14 and repeat the process: 147 / 21

Let's proceed to step 6:
21 can be fit into 147 7 times, resulting in a remainder of 0.
Write down 7 as next digit of the result. 
Result so far: 14547.0
Subtract 147 from 147 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.

Going ahead to step 7:
When dividing 0 by 21, we get 0 with a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 14547.0
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.

Let's proceed to step 8:
If we divide 0 by 21, we get 0 and a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 14547.0
If we subtract 0 from 0, 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.

The final outcome is 14547.0, with a leftover of 0.0.