Let's divide 21186 by 78
We're looking to find how many times 78 goes into 21186.

Let's proceed to step 1:
78 goes into 2 0 times with a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Fetch the next digit (1) from the dividend, attach it to 2 and continue: 21 / 78

Moving on to step 2:
When dividing 21 by 78, we get 0 with a remainder of 21.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 21 to get 21.
Take the next digit (1) from the dividend and append it to 21, then repeat: 211 / 78

Going ahead to step 3:
211 divided by 78 is 2 with a remainder of 55.
Use 2 as the next digit of our solution. 
Result so far: 2.0
The remainder is 55 after subtracting 156 from 211.
Grab the next digit (8) from the dividend, add it to 55, then carry on: 558 / 78

On to step 4:
If we divide 558 by 78, we get 7 and a remainder of 12.
Write down 7 as next digit of the result. 
Result so far: 27.0
If we take 546 away from 558, we end up with 12.
Include the next digit (6) from the dividend after 12, then repeat: 126 / 78

Going ahead to step 5:
When dividing 126 by 78, we get 1 with a remainder of 48.
Write down 1 as next digit of the result. 
Result so far: 271.0
Deduct 78 from 126 and we're left with 48.
Since there are no more digits in the dividend, we add a zero to the remainder making it 480, and continue the process.

On to step 6:
480 divided by 78 is 6 with a remainder of 12.
Put 6 as the next digit of the answer. 
Result so far: 271.6
Subtracting 468 from 480 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.

Let's proceed to step 7:
When dividing 120 by 78, we get 1 with a remainder of 42.
Use 1 as the next digit of our solution. 
Result so far: 271.61
If we take 78 away from 120, we end up with 42.
Since there are no more digits in the dividend, we add a zero to the remainder making it 420, and continue the process.

Moving on to step 8:
78 goes into 420 5 times with a remainder of 30.
Record the quotient 5 as the next digit in the result. 
Result so far: 271.615
Subtracting 390 from 420 leaves us with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Going ahead to step 9:
The number 78 fits into 300 3 times, leaving a remainder of 66.
The number 3 becomes the next digit in our result. 
Result so far: 271.6153
Subtract 234 from 300 to get 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Let's proceed to step 10:
When dividing 660 by 78, we get 8 with a remainder of 36.
The next digit of our result is 8. 
Result so far: 271.61538
Subtract 624 from 660 to get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

On to step 11:
78 can be fit into 360 4 times, resulting in a remainder of 48.
The number 4 becomes the next digit in our result. 
Result so far: 271.615384
If we subtract 312 from 360, we get 48.
Since there are no more digits in the dividend, we add a zero to the remainder making it 480, and continue the process.

On to step 12:
If we divide 480 by 78, we get 6 and a remainder of 12.
Record the quotient 6 as the next digit in the result. 
Result so far: 271.6153846
If we subtract 468 from 480, 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.

On to step 13:
78 goes into 120 1 times with a remainder of 42.
Use 1 as the next digit of our solution. 
Result so far: 271.61538461
Subtract 78 from 120 to get 42.
Since there are no more digits in the dividend, we add a zero to the remainder making it 420, and continue the process.

Our division results in 271.61538461 with a remaining 4.2e-08.