Let's divide 78885 by 21
We want to figure out the number of times 78885 can be divided by 21.

Going ahead to step 1:
The number 21 fits into 7 0 times, leaving a remainder of 7.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 7 after subtracting 0 from 7.
Include the next digit (8) from the dividend after 7, then repeat: 78 / 21

Moving on to step 2:
21 goes into 78 3 times with a remainder of 15.
Use 3 as the next digit of our solution. 
Result so far: 3.0
If we take 63 away from 78, we end up with 15.
Bring next digit (8) of the dividend behind the 15 and repeat the process: 158 / 21

Step 3:
If we divide 158 by 21, we get 7 and a remainder of 11.
Use 7 as the next digit of our solution. 
Result so far: 37.0
The remainder is 11 after subtracting 147 from 158.
Bring next digit (8) of the dividend behind the 11 and repeat the process: 118 / 21

Going ahead to step 4:
If we divide 118 by 21, we get 5 and a remainder of 13.
Write down 5 as next digit of the result. 
Result so far: 375.0
Deduct 105 from 118 and we're left with 13.
Take the next digit (5) from the dividend and append it to 13, then repeat: 135 / 21

Advancing to step 5:
If we divide 135 by 21, we get 6 and a remainder of 9.
The number 6 becomes the next digit in our result. 
Result so far: 3756.0
The remainder is 9 after subtracting 126 from 135.
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 6:
21 goes into 90 4 times with a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 3756.4
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Advancing to step 7:
If we divide 60 by 21, we get 2 and a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 3756.42
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Let's proceed to step 8:
If we divide 180 by 21, we get 8 and a remainder of 12.
The next digit of our result is 8. 
Result so far: 3756.428
If we subtract 168 from 180, we 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.

Let's proceed to step 9:
If we divide 120 by 21, we get 5 and a remainder of 15.
Put 5 as the next digit of the answer. 
Result so far: 3756.4285
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.

On to step 10:
150 divided by 21 is 7 with a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 3756.42857
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.

Going ahead to step 11:
When dividing 30 by 21, we get 1 with a remainder of 9.
The next digit of our result is 1. 
Result so far: 3756.428571
Subtracting 21 from 30 leaves us 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.

On to step 12:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 3756.4285714
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Going ahead to step 13:
21 goes into 60 2 times with a remainder of 18.
Write down 2 as next digit of the result. 
Result so far: 3756.42857142
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.

After the division, we end up with 3756.42857142 and a remainder of 1.8e-08.