We're dividing 51631 by 21 
Let's see how many times 21 fits into 51631.

Moving on to step 1:
When dividing 5 by 21, we get 0 with a remainder of 5.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 5, we get 5.
Include the next digit (1) from the dividend after 5, then repeat: 51 / 21

On to step 2:
When dividing 51 by 21, we get 2 with a remainder of 9.
The next digit of our result is 2. 
Result so far: 2.0
If we take 42 away from 51, we end up with 9.
Bring next digit (6) of the dividend behind the 9 and repeat the process: 96 / 21

Let's proceed to step 3:
21 goes into 96 4 times with a remainder of 12.
Put 4 as the next digit of the answer. 
Result so far: 24.0
The remainder is 12 after subtracting 84 from 96.
Include the next digit (3) from the dividend after 12, then repeat: 123 / 21

Advancing to step 4:
123 divided by 21 is 5 with a remainder of 18.
The next digit of our result is 5. 
Result so far: 245.0
Deduct 105 from 123 and we're left with 18.
Bring next digit (1) of the dividend behind the 18 and repeat the process: 181 / 21

Moving on to step 5:
The number 21 fits into 181 8 times, leaving a remainder of 13.
Put 8 as the next digit of the answer. 
Result so far: 2458.0
The remainder is 13 after subtracting 168 from 181.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Going ahead to step 6:
The number 21 fits into 130 6 times, leaving a remainder of 4.
The number 6 becomes the next digit in our result. 
Result so far: 2458.6
Subtracting 126 from 130 leaves us 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.

Step 7:
21 goes into 40 1 times with a remainder of 19.
Record the quotient 1 as the next digit in the result. 
Result so far: 2458.61
Subtracting 21 from 40 leaves us with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 8:
When dividing 190 by 21, we get 9 with a remainder of 1.
Write down 9 as next digit of the result. 
Result so far: 2458.619
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.

Advancing to step 9:
21 can be fit into 10 0 times, resulting in a remainder of 10.
Write down 0 as next digit of the result. 
Result so far: 2458.619
Deduct 0 from 10 and we're left with 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 10:
100 divided by 21 is 4 with a remainder of 16.
Record the quotient 4 as the next digit in the result. 
Result so far: 2458.61904
If we take 84 away from 100, we end up with 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 11:
160 divided by 21 is 7 with a remainder of 13.
Use 7 as the next digit of our solution. 
Result so far: 2458.619047
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.

Step 12:
The number 21 fits into 130 6 times, leaving a remainder of 4.
Use 6 as the next digit of our solution. 
Result so far: 2458.6190476
If we take 126 away from 130, we end up 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.

Step 13:
The number 21 fits into 40 1 times, leaving a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 2458.61904761
The remainder is 19 after subtracting 21 from 40.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Our division results in 2458.61904761 with a remaining 1.9e-08.