Let's divide 31359 by 21
Our goal is to divide 31359 by 21.

On to step 1:
When dividing 3 by 21, we get 0 with a remainder of 3.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 3 leaves us with 3.
Append the next digit (1) from the dividend to 3 and continue with: 31 / 21

Going ahead to step 2:
21 can be fit into 31 1 times, resulting in a remainder of 10.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we subtract 21 from 31, we get 10.
Take the next digit (3) from the dividend and append it to 10, then repeat: 103 / 21

Moving on to step 3:
103 divided by 21 is 4 with a remainder of 19.
Put 4 as the next digit of the answer. 
Result so far: 14.0
Subtract 84 from 103 to get 19.
Include the next digit (5) from the dividend after 19, then repeat: 195 / 21

Going ahead to step 4:
195 divided by 21 is 9 with a remainder of 6.
The next digit of our result is 9. 
Result so far: 149.0
If we take 189 away from 195, we end up with 6.
Append the next digit (9) from the dividend to 6 and continue with: 69 / 21

Step 5:
If we divide 69 by 21, we get 3 and a remainder of 6.
Put 3 as the next digit of the answer. 
Result so far: 1493.0
If we take 63 away from 69, 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.

Moving on to step 6:
21 can be fit into 60 2 times, resulting in a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 1493.2
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.

Let's proceed to step 7:
21 goes into 180 8 times with a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 1493.28
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.

Going ahead to step 8:
If we divide 120 by 21, we get 5 and a remainder of 15.
Use 5 as the next digit of our solution. 
Result so far: 1493.285
The remainder is 15 after subtracting 105 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 9:
When dividing 150 by 21, we get 7 with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 1493.2857
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.

Let's proceed to step 10:
When dividing 30 by 21, we get 1 with a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 1493.28571
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.

Going ahead to step 11:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 1493.285714
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.

Going ahead to step 12:
21 goes into 60 2 times with a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 1493.2857142
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.

On to step 13:
180 divided by 21 is 8 with a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 1493.28571428
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.

After the division, we end up with 1493.28571428 and a remainder of 1.2e-08.