310518 divided by 21 
We're looking to find how many times 21 goes into 310518.

Let's proceed to step 1:
When dividing 3 by 21, we get 0 with 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.
Grab the next digit (1) from the dividend, add it to 3, then carry on: 31 / 21

Advancing to step 2:
31 divided by 21 is 1 with 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.
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.
Take the next digit (5) from the dividend and append it to 16, then repeat: 165 / 21

Advancing to step 4:
165 divided by 21 is 7 with a remainder of 18.
Write down 7 as next digit of the result. 
Result so far: 147.0
If we take 147 away from 165, we end up with 18.
Bring next digit (1) of the dividend behind the 18 and repeat the process: 181 / 21

Going ahead to step 5:
181 divided by 21 is 8 with a remainder of 13.
The next digit of our result is 8. 
Result so far: 1478.0
If we subtract 168 from 181, we get 13.
Bring next digit (8) of the dividend behind the 13 and repeat the process: 138 / 21

Step 6:
If we divide 138 by 21, we get 6 and a remainder of 12.
Write down 6 as next digit of the result. 
Result so far: 14786.0
The remainder is 12 after subtracting 126 from 138.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 7:
If we divide 120 by 21, we get 5 and a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 14786.5
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.

Let's proceed to step 8:
21 goes into 150 7 times with a remainder of 3.
Write down 7 as next digit of the result. 
Result so far: 14786.57
If we subtract 147 from 150, we 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.

Step 9:
The number 21 fits into 30 1 times, leaving a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 14786.571
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.

On to step 10:
If we divide 90 by 21, we get 4 and a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 14786.5714
Deduct 84 from 90 and we're left 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.

Going ahead to step 11:
60 divided by 21 is 2 with a remainder of 18.
Write down 2 as next digit of the result. 
Result so far: 14786.57142
Deduct 42 from 60 and we're left 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:
180 divided by 21 is 8 with a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 14786.571428
Deduct 168 from 180 and we're left 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.

Going ahead to step 13:
21 can be fit into 120 5 times, resulting in a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 14786.5714285
Subtracting 105 from 120 leaves us 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.

Going ahead to step 14:
When dividing 150 by 21, we get 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 14786.57142857
Deduct 147 from 150 and we're left 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 14786.57142857 with a remaining 3e-09.