Let's divide 765171 by 21
We're looking to find how many times 21 goes into 765171.

Advancing to step 1:
The number 21 fits into 7 0 times, leaving a remainder of 7.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 7 and we're left with 7.
Bring next digit (6) of the dividend behind the 7 and repeat the process: 76 / 21

On to step 2:
When dividing 76 by 21, we get 3 with a remainder of 13.
The number 3 becomes the next digit in our result. 
Result so far: 3.0
If we subtract 63 from 76, we get 13.
Append the next digit (5) from the dividend to 13 and continue with: 135 / 21

Moving on to step 3:
When dividing 135 by 21, we get 6 with a remainder of 9.
Record the quotient 6 as the next digit in the result. 
Result so far: 36.0
Subtracting 126 from 135 leaves us with 9.
Take the next digit (1) from the dividend and append it to 9, then repeat: 91 / 21

Going ahead to step 4:
91 divided by 21 is 4 with a remainder of 7.
Put 4 as the next digit of the answer. 
Result so far: 364.0
If we subtract 84 from 91, we get 7.
Grab the next digit (7) from the dividend, add it to 7, then carry on: 77 / 21

On to step 5:
If we divide 77 by 21, we get 3 and a remainder of 14.
Record the quotient 3 as the next digit in the result. 
Result so far: 3643.0
Subtracting 63 from 77 leaves us with 14.
Bring next digit (1) of the dividend behind the 14 and repeat the process: 141 / 21

Step 6:
141 divided by 21 is 6 with a remainder of 15.
The next digit of our result is 6. 
Result so far: 36436.0
Deduct 126 from 141 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 7:
21 goes into 150 7 times with a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 36436.7
Subtract 147 from 150 to 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.

Advancing to step 8:
21 can be fit into 30 1 times, resulting in a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 36436.71
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.

Moving on to step 9:
If we divide 90 by 21, we get 4 and a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 36436.714
Subtract 84 from 90 to 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.

Let's proceed to step 10:
The number 21 fits into 60 2 times, leaving a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 36436.7142
If we subtract 42 from 60, we get 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 11:
180 divided by 21 is 8 with a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 36436.71428
Subtract 168 from 180 to get 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 12:
21 goes into 120 5 times with a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 36436.714285
Subtract 105 from 120 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Let's proceed to step 13:
When dividing 150 by 21, we get 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 36436.7142857
If we take 147 away from 150, we end up 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.

On to step 14:
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: 36436.71428571
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.

The final outcome is 36436.71428571, with a leftover of 9e-09.