We look at the division of 312549 by 21 
Let's see how many times 21 fits into 312549.

Let's proceed to step 1:
If we divide 3 by 21, we get 0 and 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.
Include the next digit (1) from the dividend after 3, then repeat: 31 / 21

Going ahead to step 2:
21 can be fit into 31 1 times, resulting in a remainder of 10.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we subtract 21 from 31, we get 10.
Include the next digit (2) from the dividend after 10, then repeat: 102 / 21

Going ahead to step 3:
The number 21 fits into 102 4 times, leaving a remainder of 18.
Record the quotient 4 as the next digit in the result. 
Result so far: 14.0
Subtracting 84 from 102 leaves us with 18.
Include the next digit (5) from the dividend after 18, then repeat: 185 / 21

Advancing to step 4:
21 can be fit into 185 8 times, resulting in a remainder of 17.
The number 8 becomes the next digit in our result. 
Result so far: 148.0
The remainder is 17 after subtracting 168 from 185.
Append the next digit (4) from the dividend to 17 and continue with: 174 / 21

Step 5:
If we divide 174 by 21, we get 8 and a remainder of 6.
Use 8 as the next digit of our solution. 
Result so far: 1488.0
If we take 168 away from 174, we end up with 6.
Bring next digit (9) of the dividend behind the 6 and repeat the process: 69 / 21

Going ahead to step 6:
21 goes into 69 3 times with a remainder of 6.
The number 3 becomes the next digit in our result. 
Result so far: 14883.0
The remainder is 6 after subtracting 63 from 69.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 7:
The number 21 fits into 60 2 times, leaving a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 14883.2
Subtracting 42 from 60 leaves us with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Advancing to step 8:
21 goes into 180 8 times with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 14883.28
If we subtract 168 from 180, we get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Let's proceed to step 9:
21 can be fit into 120 5 times, resulting in a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 14883.285
Subtract 105 from 120 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Step 10:
If we divide 150 by 21, we get 7 and a remainder of 3.
Record the quotient 7 as the next digit in the result. 
Result so far: 14883.2857
Subtract 147 from 150 to get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Going ahead to step 11:
The number 21 fits into 30 1 times, leaving a remainder of 9.
The next digit of our result is 1. 
Result so far: 14883.28571
Subtract 21 from 30 to get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Moving on to step 12:
When dividing 90 by 21, we get 4 with a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 14883.285714
Subtracting 84 from 90 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Advancing to step 13:
The number 21 fits into 60 2 times, leaving a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 14883.2857142
If we subtract 42 from 60, we get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Moving on to step 14:
When dividing 180 by 21, we get 8 with a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 14883.28571428
If we take 168 away from 180, we end up with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Our division results in 14883.28571428 with a remaining 1.2e-08.