Let's divide 320121 by 21
Our goal is to divide 320121 by 21.

On to step 1:
3 divided by 21 is 0 with a remainder of 3.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 3 and we're left with 3.
Include the next digit (2) from the dividend after 3, then repeat: 32 / 21

Advancing to step 2:
If we divide 32 by 21, we get 1 and a remainder of 11.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we subtract 21 from 32, we get 11.
Fetch the next digit (0) from the dividend, attach it to 11 and continue: 110 / 21

On to step 3:
If we divide 110 by 21, we get 5 and a remainder of 5.
Write down 5 as next digit of the result. 
Result so far: 15.0
Subtract 105 from 110 to get 5.
Take the next digit (1) from the dividend and append it to 5, then repeat: 51 / 21

Moving on to step 4:
51 divided by 21 is 2 with a remainder of 9.
Write down 2 as next digit of the result. 
Result so far: 152.0
If we take 42 away from 51, we end up with 9.
Append the next digit (2) from the dividend to 9 and continue with: 92 / 21

Let's proceed to step 5:
92 divided by 21 is 4 with a remainder of 8.
Record the quotient 4 as the next digit in the result. 
Result so far: 1524.0
Subtracting 84 from 92 leaves us with 8.
Include the next digit (1) from the dividend after 8, then repeat: 81 / 21

Moving on to step 6:
81 divided by 21 is 3 with a remainder of 18.
Write down 3 as next digit of the result. 
Result so far: 15243.0
If we take 63 away from 81, we end up 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 7:
When dividing 180 by 21, we get 8 with a remainder of 12.
The next digit of our result is 8. 
Result so far: 15243.8
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.

Advancing to step 8:
21 can be fit into 120 5 times, resulting in a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 15243.85
Deduct 105 from 120 and we're left 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.

Step 9:
The number 21 fits into 150 7 times, leaving a remainder of 3.
Record the quotient 7 as the next digit in the result. 
Result so far: 15243.857
The remainder is 3 after subtracting 147 from 150.
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:
21 goes into 30 1 times with a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 15243.8571
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:
21 can be fit into 90 4 times, resulting in a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 15243.85714
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

On to step 12:
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: 15243.857142
The remainder is 18 after subtracting 42 from 60.
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:
21 can be fit into 180 8 times, resulting in a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 15243.8571428
The remainder is 12 after subtracting 168 from 180.
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 14:
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: 15243.85714285
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.

The final result is 15243.85714285 with a remainder of 1.5e-08.