We look at the division of 651810 by 21 
We want to figure out the number of times 651810 can be divided by 21.

On to step 1:
21 can be fit into 6 0 times, resulting in a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Bring next digit (5) of the dividend behind the 6 and repeat the process: 65 / 21

Going ahead to step 2:
The number 21 fits into 65 3 times, leaving a remainder of 2.
Put 3 as the next digit of the answer. 
Result so far: 3.0
Deduct 63 from 65 and we're left with 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 21

Moving on to step 3:
21 divided by 21 is 1 with a remainder of 0.
The next digit of our result is 1. 
Result so far: 31.0
Deduct 21 from 21 and we're left with 0.
Append the next digit (8) from the dividend to 0 and continue with: 8 / 21

On to step 4:
8 divided by 21 is 0 with a remainder of 8.
Use 0 as the next digit of our solution. 
Result so far: 310.0
Deduct 0 from 8 and we're left with 8.
Grab the next digit (1) from the dividend, add it to 8, then carry on: 81 / 21

Going ahead to step 5:
When dividing 81 by 21, we get 3 with a remainder of 18.
Put 3 as the next digit of the answer. 
Result so far: 3103.0
If we subtract 63 from 81, we get 18.
Include the next digit (0) from the dividend after 18, then repeat: 180 / 21

Going ahead to step 6:
180 divided by 21 is 8 with a remainder of 12.
The next digit of our result is 8. 
Result so far: 31038.0
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.

Moving on to step 7:
21 can be fit into 120 5 times, resulting in a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 31038.5
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 8:
21 can be fit into 150 7 times, resulting in a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 31038.57
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.

Going ahead to step 9:
21 can be fit into 30 1 times, resulting in a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 31038.571
If we take 21 away from 30, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Let's proceed to step 10:
21 goes into 90 4 times with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 31038.5714
If we subtract 84 from 90, we get 6.
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 11:
21 goes into 60 2 times with a remainder of 18.
The next digit of our result is 2. 
Result so far: 31038.57142
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 next digit of our result is 8. 
Result so far: 31038.571428
Subtracting 168 from 180 leaves us 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.

Moving on to step 13:
When dividing 120 by 21, we get 5 with a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 31038.5714285
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.

Advancing to step 14:
21 can be fit into 150 7 times, resulting in a remainder of 3.
Use 7 as the next digit of our solution. 
Result so far: 31038.57142857
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.

After the division, we end up with 31038.57142857 and a remainder of 3e-09.