310749 divided by 21 
Let's see how many times 21 fits into 310749.

Going ahead to step 1:
The number 21 fits into 3 0 times, leaving a remainder of 3.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 3 leaves us with 3.
Fetch the next digit (1) from the dividend, attach it to 3 and continue: 31 / 21

Step 2:
If we divide 31 by 21, we get 1 and a remainder of 10.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
If we subtract 21 from 31, we get 10.
Fetch the next digit (0) from the dividend, attach it to 10 and continue: 100 / 21

Going ahead to step 3:
21 can be fit into 100 4 times, resulting in a remainder of 16.
Put 4 as the next digit of the answer. 
Result so far: 14.0
Deduct 84 from 100 and we're left with 16.
Append the next digit (7) from the dividend to 16 and continue with: 167 / 21

Moving on to step 4:
The number 21 fits into 167 7 times, leaving a remainder of 20.
Use 7 as the next digit of our solution. 
Result so far: 147.0
If we subtract 147 from 167, we get 20.
Grab the next digit (4) from the dividend, add it to 20, then carry on: 204 / 21

Moving on to step 5:
If we divide 204 by 21, we get 9 and a remainder of 15.
Record the quotient 9 as the next digit in the result. 
Result so far: 1479.0
Deduct 189 from 204 and we're left with 15.
Grab the next digit (9) from the dividend, add it to 15, then carry on: 159 / 21

Step 6:
The number 21 fits into 159 7 times, leaving a remainder of 12.
The next digit of our result is 7. 
Result so far: 14797.0
The remainder is 12 after subtracting 147 from 159.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Advancing to step 7:
The number 21 fits into 120 5 times, leaving a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 14797.5
If we take 105 away from 120, we end up with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 8:
21 goes into 150 7 times with a remainder of 3.
The next digit of our result is 7. 
Result so far: 14797.57
If we take 147 away from 150, we end up with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Advancing to step 9:
If we divide 30 by 21, we get 1 and a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 14797.571
Subtracting 21 from 30 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 10:
21 goes into 90 4 times with a remainder of 6.
The next digit of our result is 4. 
Result so far: 14797.5714
If we take 84 away from 90, we end up 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.

Let's proceed to step 11:
If we divide 60 by 21, we get 2 and a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 14797.57142
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.

Going ahead to step 12:
21 goes into 180 8 times with a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 14797.571428
Subtracting 168 from 180 leaves us 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.

On to step 13:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 14797.5714285
If we take 105 away from 120, we end up with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Moving on to step 14:
21 goes into 150 7 times with a remainder of 3.
Record the quotient 7 as the next digit in the result. 
Result so far: 14797.57142857
Subtracting 147 from 150 leaves us with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Our division results in 14797.57142857 with a remaining 3e-09.