We're dividing 319399 by 21 
We want to figure out the number of times 319399 can be divided by 21.

Advancing to step 1:
3 divided by 21 is 0 with a remainder of 3.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 3, we end up with 3.
Include the next digit (1) from the dividend after 3, then repeat: 31 / 21

Advancing to step 2:
21 goes into 31 1 times with a remainder of 10.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtracting 21 from 31 leaves us with 10.
Take the next digit (9) from the dividend and append it to 10, then repeat: 109 / 21

Let's proceed to step 3:
21 goes into 109 5 times with a remainder of 4.
Record the quotient 5 as the next digit in the result. 
Result so far: 15.0
Subtract 105 from 109 to get 4.
Include the next digit (3) from the dividend after 4, then repeat: 43 / 21

Moving on to step 4:
43 divided by 21 is 2 with a remainder of 1.
The number 2 becomes the next digit in our result. 
Result so far: 152.0
If we take 42 away from 43, we end up with 1.
Include the next digit (9) from the dividend after 1, then repeat: 19 / 21

Going ahead to step 5:
If we divide 19 by 21, we get 0 and a remainder of 19.
The next digit of our result is 0. 
Result so far: 1520.0
Subtract 0 from 19 to get 19.
Include the next digit (9) from the dividend after 19, then repeat: 199 / 21

Going ahead to step 6:
The number 21 fits into 199 9 times, leaving a remainder of 10.
Write down 9 as next digit of the result. 
Result so far: 15209.0
The remainder is 10 after subtracting 189 from 199.
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 7:
When dividing 100 by 21, we get 4 with a remainder of 16.
Use 4 as the next digit of our solution. 
Result so far: 15209.4
If we subtract 84 from 100, we get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 8:
21 can be fit into 160 7 times, resulting in a remainder of 13.
The next digit of our result is 7. 
Result so far: 15209.47
Subtract 147 from 160 to get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Moving on to step 9:
If we divide 130 by 21, we get 6 and a remainder of 4.
Put 6 as the next digit of the answer. 
Result so far: 15209.476
Deduct 126 from 130 and we're left with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Moving on to step 10:
21 goes into 40 1 times with a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 15209.4761
If we subtract 21 from 40, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Let's proceed to step 11:
If we divide 190 by 21, we get 9 and a remainder of 1.
The number 9 becomes the next digit in our result. 
Result so far: 15209.47619
If we subtract 189 from 190, 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.

Moving on to step 12:
21 can be fit into 10 0 times, resulting in a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 15209.47619
Subtract 0 from 10 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 13:
When dividing 100 by 21, we get 4 with a remainder of 16.
Use 4 as the next digit of our solution. 
Result so far: 15209.4761904
Subtract 84 from 100 to get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

On to step 14:
21 can be fit into 160 7 times, resulting in a remainder of 13.
The next digit of our result is 7. 
Result so far: 15209.47619047
If we take 147 away from 160, we end up with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Our division results in 15209.47619047 with a remaining 1.3e-08.