781596 ÷ 21 
We're looking to find how many times 21 goes into 781596.

Step 1:
The number 21 fits into 7 0 times, leaving a remainder of 7.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 7 leaves us with 7.
Bring next digit (8) of the dividend behind the 7 and repeat the process: 78 / 21

On to step 2:
When dividing 78 by 21, we get 3 with a remainder of 15.
Put 3 as the next digit of the answer. 
Result so far: 3.0
The remainder is 15 after subtracting 63 from 78.
Include the next digit (1) from the dividend after 15, then repeat: 151 / 21

Advancing to step 3:
151 divided by 21 is 7 with a remainder of 4.
Put 7 as the next digit of the answer. 
Result so far: 37.0
If we take 147 away from 151, we end up with 4.
Take the next digit (5) from the dividend and append it to 4, then repeat: 45 / 21

Going ahead to step 4:
21 goes into 45 2 times with a remainder of 3.
Write down 2 as next digit of the result. 
Result so far: 372.0
Subtract 42 from 45 to get 3.
Grab the next digit (9) from the dividend, add it to 3, then carry on: 39 / 21

Moving on to step 5:
When dividing 39 by 21, we get 1 with a remainder of 18.
The next digit of our result is 1. 
Result so far: 3721.0
Subtracting 21 from 39 leaves us with 18.
Bring next digit (6) of the dividend behind the 18 and repeat the process: 186 / 21

Moving on to step 6:
When dividing 186 by 21, we get 8 with a remainder of 18.
The number 8 becomes the next digit in our result. 
Result so far: 37218.0
If we take 168 away from 186, 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.

Going ahead to step 7:
21 goes into 180 8 times with a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 37218.8
Deduct 168 from 180 and we're left 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.

Step 8:
The number 21 fits into 120 5 times, leaving a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 37218.85
If we take 105 away from 120, we end up 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 9:
When dividing 150 by 21, we get 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 37218.857
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.

Step 10:
If we divide 30 by 21, we get 1 and a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 37218.8571
If we subtract 21 from 30, we 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 goes into 90 4 times with a remainder of 6.
Use 4 as the next digit of our solution. 
Result so far: 37218.85714
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.

On to step 12:
21 can be fit into 60 2 times, resulting in a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 37218.857142
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.

Moving on to step 13:
The number 21 fits into 180 8 times, leaving a remainder of 12.
The number 8 becomes the next digit in our result. 
Result so far: 37218.8571428
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.

Step 14:
120 divided by 21 is 5 with a remainder of 15.
The number 5 becomes the next digit in our result. 
Result so far: 37218.85714285
If we take 105 away from 120, we end up 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.

After the division, we end up with 37218.85714285 and a remainder of 1.5e-08.