We divide 778120 by 21
We want to figure out the number of times 778120 can be divided by 21.

Step 1:
21 can be fit into 7 0 times, resulting in 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.
Grab the next digit (7) from the dividend, add it to 7, then carry on: 77 / 21

Going ahead to step 2:
If we divide 77 by 21, we get 3 and a remainder of 14.
Write down 3 as next digit of the result. 
Result so far: 3.0
Deduct 63 from 77 and we're left with 14.
Take the next digit (8) from the dividend and append it to 14, then repeat: 148 / 21

On to step 3:
If we divide 148 by 21, we get 7 and a remainder of 1.
The number 7 becomes the next digit in our result. 
Result so far: 37.0
Subtract 147 from 148 to get 1.
Grab the next digit (1) from the dividend, add it to 1, then carry on: 11 / 21

Moving on to step 4:
11 divided by 21 is 0 with a remainder of 11.
The number 0 becomes the next digit in our result. 
Result so far: 370.0
If we take 0 away from 11, we end up with 11.
Include the next digit (2) from the dividend after 11, then repeat: 112 / 21

Moving on to step 5:
The number 21 fits into 112 5 times, leaving a remainder of 7.
The next digit of our result is 5. 
Result so far: 3705.0
If we subtract 105 from 112, we get 7.
Bring next digit (0) of the dividend behind the 7 and repeat the process: 70 / 21

Advancing to step 6:
When dividing 70 by 21, we get 3 with a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 37053.0
Deduct 63 from 70 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

On to step 7:
If we divide 70 by 21, we get 3 and a remainder of 7.
The number 3 becomes the next digit in our result. 
Result so far: 37053.3
If we take 63 away from 70, we end up with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Going ahead to step 8:
If we divide 70 by 21, we get 3 and a remainder of 7.
The number 3 becomes the next digit in our result. 
Result so far: 37053.33
Subtract 63 from 70 to get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Our division results in 37053.33 with a remaining 0.007.